Help me understand this Minor Illusion "Inviisibility" trick!

[Coffee_Dragon]

I'm not super convinced by arguments that go "this must be so because common sense/physics, and this must be so because common sense/physics, but this thing here is wonky so that's magic".

I also never bought the "illusions must reflect light or they'd be black cutouts" argument; I just assume the inability to shed light refers to an inability to change ambient light levels. So how does it visually fit into the environment? To some extent it's magic, and to some extent it's imperfect.

[Dr.Samurai]

Nah, that idea is silly. It's too clever by half - and is the typical 'power creep' that you see in a 'rulings not rules' game where hundreds of thousands of words aren't devoted to legalistic mumbo jumbo.

It's also a way to pretend you're being clever when you're really just being complicated. Clever means solving a problem in the easiest way.

Just crouch down and become a small chest of drawers. Or a stack of firewood.

I pretty much agree with this sentiment as far as this trick is concerned.

@Prophes0r: I don't have much of an issue with what you said, except that I don't really get how you determine at what point you can just chalk it up to "it's magic". It seems to me, that illusions can work as you describe without anyone having to think about real world physics for even a second. I have never thought too hard about how illusions work. I always assumed they would accurately reflect the lighting of the room they are in. I think, intuitively, people get that the lighting and shadowing are there, despite Crawford saying to ask your DM. This all really just seems like an attempt to explain how an illusory mirror is actually just a real mirror that you can't interact with. That's... not what it is. So we get this entire appeal to science which just sort of confuses everything. All of this is to say that although your post is articulated well and I largely agree with you, at some point we will always have to fall back on "it's a spell, it's a magic effect", which makes the science argument moot in my opinion.

[Dalebert]

If you stick to the RAW, it is actually quite simple. What complicates the Hell out of it are arbitrary exceptions to what you'd normally expect like that it doesn't cast shadows.

RAW:
* Has to be an object (not a creature)
* Must fit into a 5 x 5 x 5 cube
* Can't shed light so a mirror is fine but a lit torch is not
* You can figure out it's an illusion by physically interacting with it or by successfully investigating it with your action

Checking whether it casts a shadow is not in there as a way to determine it's an illusion. If that's added, the spell is pointless.

[ThePolarBear]

If an object doesn't obey the laws of physics (Which according to Mearls and Crawford these illusions don't) you're bound to notice them. When the word of God literally says "These things do not interact with light like real objects" all the statements of "Magic!" in the world won't save them.

Correct. But we are not talking about objects, but about ILLUSIONS. There's a world of difference, and in that world of distance "Magic" is the answer you are looking for.

Also remember: Minor illusion does not cast a shadow. That's what the tweet provided tells us.
This does not mean that all the illusions cannot cast a shadow or cannot be made to cast realistic shadows.

Personally when i encounter this kind on "nonsense" i do not try to apply too much "real" physics logic because that's something that simply cannot be done - Magic is something that (for all i know :D) simply does not exists in this world. We cannot apply any kind of common sense to this kind of discussions. We do not know how magic works if not for the boundaries given by RAW and RAI. We pick what we like the most.

For me, spells that do not allow interaction or that cannot be made to be "animated" are not able to be used for things like mirrors - and even then the ones that are "animated" can fool only one creature and it's still difficult to perform. There are no shadows cast by Minor Image's illusionary objects - but that's up to the player to come up with reasonable positioning of said illusion to make it "believable". The spell, in its limitations, will take care of the rest.

[kulosle]

If you stick to the RAW, it is actually quite simple. What complicates the Hell out of it are arbitrary exceptions to what you'd normally expect like that it doesn't cast shadows.

RAW:
* Has to be an object (not a creature)
* Must fit into a 5 x 5 x 5 cube
* Can't shed light so a mirror is fine but a lit torch is not
* You can figure out it's an illusion by physically interacting with it or by successfully investigating it with your action

Checking whether it casts a shadow is not in there as a way to determine it's an illusion. If that's added, the spell is pointless.

I like this point the best. The spell doesn't offer any extra ways of being able to tell that it is an illusion. You have to interact with it or decide to investigate it. There isn't a reason to not believe it unless you do one of those things.

If illusions were as obviously not real as some would suggest they would be fairly terrible. And a lot less fun.

[lperkins2]

So, it seems that the sticking point is the no 'any other sensory effect' phrase. If the spell cannot create any sensory effect, it may as well not exist, since seeing it is a sensory effect. If the illusion can be seen, light bouncing off of it does not count as creating a sensory effect for the purposes of this spell. It says it cannot create light, so the only other possibility is it reflects light (or is always matte black). The only way to interpret it that makes any sense is that it cannot emit more light than it absorbs, that is it cannot glow like a torch. Given that it can reflect light the only question which remains is what is the upper limit on the created image's albedo. Since nothing specifies an upper limit, I see no reason it could not be somewhere near 1. Note that if an illusionary coin glints in the torchlight, it is reflective enough to make a mirror.

The only way I could see it working differently is if it is like 3.5 where it is mind-affecting, but then I would expect things immune to charm-effects to see through it automatically.

I'm not trying to insert real-world physics into it, just pointing out the dichotomy of no glinting anything (coins, hinges, swords) or allowing mirrors.

Edit: If it is reflecting a portion of the light back (which it must, since it produces no light of its own and is not matte black), it must cast a shadow.

[Cybren]

I like this point the best. The spell doesn't offer any extra ways of being able to tell that it is an illusion. You have to interact with it or decide to investigate it. There isn't a reason to not believe it unless you do one of those things.

If illusions were as obviously not real as some would suggest they would be fairly terrible. And a lot less fun.

Of course, not having a shadow isn't proof something is an illusion, since this is a world where shadows, treasure chests, and stalactites might try to eat you.

[Dr.Samurai]

I'm not trying to insert real-world physics into it, just pointing out the dichotomy of no glinting anything (coins, hinges, swords) or allowing mirrors.

Edit: If it is reflecting a portion of the light back (which it must, since it produces no light of its own and is not matte black), it must cast a shadow.

Please explain to me what the light is reflecting off of when it hits the illusion. What surface is it striking and bouncing off of?

[Dalebert]

Please explain to me what the light is reflecting off of when it hits the illusion. What surface is it striking and bouncing off of?

No. It's pointless to explain. It's magic!

Okay, fine. I'll explain it a little bit as best I can based on what we know about how the spell works.

We know it's creating a sensory effect because it's not in your mind like Phantasmal Force. The spell is creating a visual sensory effect that everything nearby can see. We know it's not able to emit light because this spell specifically says the object can't emit light. This means it can only reflect existing light (or whatever darkvision picks up) the same way that solid objects do in order to create the visual sensory effect of an actual object in that spot.

[lperkins2]

No. It's pointless to explain. It's magic!

Okay, fine. I'll explain it a little bit as best I can based on what we know about how the spell works.

We know it's creating a sensory effect because it's not in your mind like Phantasmal Force. The spell is creating a visual sensory effect that everything nearby can see. We know it's not able to emit light because this spell specifically says the object can't emit light. This means it can only reflect existing light (or whatever darkvision picks up) the same way that solid objects do in order to create the visual sensory effect of an actual object in that spot.

Pretty much. Strictly, it might not be reflecting light, it might only refract it, or absorb it on one side and re-emit it on the other. The problem is anything except basic, ordinary reflection is likely to make it painfully obvious that it is an illusion. If it was no-casting-a-shadow painfully obvious it's an illusion, it wouldn't require any check to know it's fake (like modern holograms, which are painfully obviously not solid).

[Sabeta]

@Dalebert: The spell doesn't create sensory effects. That's 100% RAW. You arguing that visibility being a sensory effect actually supports the idea that the spell is purely mental over the idea that the rules and the devs are mistaken. It doesn't cast shadows because objects, including the physical aspect of light, passes through it.

The book says this. The devs elaborated on it because people like you didn't get it. Then you said " no. you, who wrote the book on how the game is meant to be played, do not know what you're talking about. The guy whose job it is to clarify the rules doesn't understand the rules."

Quite frankly, it's hilarious how far people go just to rules lawyer a cantrip.

@Punkette: Common sense isn't always common. I found the RAW clear, and the SA supported my stance. This thread exists because not everyone shares the same level of reading comprehension.

[Dr.Samurai]

We know it's creating a sensory effect because it's not in your mind like Phantasmal Force. The spell is creating a visual sensory effect that everything nearby can see.

Um... I guess. I don't see any reason to refer to it as a "visual sensory effect" when it is called an image. But ok.

We know it's not able to emit light because this spell specifically says the object can't emit light.

Yeah ok.

This means it can only reflect existing light

No that's not what that means.

the same way that solid objects do in order to create the visual sensory effect of an actual object in that spot.

How can it possibly reflect existing light the same way a solid object does if it literally has NONE of the properties of any solid object?

What you are suggesting is that you're conjuring some sort of intangible object into existence that operates like other physical tangible things, but can't be touched. That's not what the illusion is. There is *literally* no surface for light to bounce off of the illusion. It's not really there. It doesn't exist. It. is. an. illusion.

You're willing to delve into the science to justify working mirrors, but you fail to explain how exactly the illusion is reflecting the light that you require *must* be reflected.

It's magic. That's all the explanation you need. The wizard is creating a magical effect (the image) that somehow makes you see what he wants you to see, within the constraints of the spell. It doesn't do this by reflecting back light to you, because there is literally nothing there for the light to bounce off.

[Dr.Samurai]

Pretty much. Strictly, it might not be reflecting light, it might only refract it, or absorb it on one side and re-emit it on the other.

How can it do any of these things? Seriously, if you're going to bring in science to invent a problem that justifies working mirrors, then stick to the science and explain how the light can be reflected, refracted, or absorbed in any way by an illusion.

The problem is anything except basic, ordinary reflection is likely to make it painfully obvious that it is an illusion.

Which is fine. Why should the cantrip be fool-proof?

If it was no-casting-a-shadow painfully obvious it's an illusion, it wouldn't require any check to know it's fake (like modern holograms, which are painfully obviously not solid).

You create an image. Presumably, the wizard, very smart and learned in magic, can craft some pretty good images. So you make the image and if someone isn't paying close attention (spending that action) or touching it, they don't notice it, lack of shadows and all. I'm not seeing the big problem here.

[Coidzor]

I'm with Cybren on this. It's magic. There is no reason to restrain ourselves to these two possibilities.

But you see a reason to restrain yourself to the idea that illusions aren't capable of anything a computer screen isn't?

It's interesting that people are having so much trouble with this. My group has apparently been playing with a house rule I guess. It's not something that even cares about light. The illusion isn't an object. So why even question if it interacts with light. Other wise the illusion would still be there if you disbelieved it. So it's magic nonsense. It's all in the person's head. It's not a real thing. You are tricking someone's brain into thinking something is real that isn't. You don't have to draw a picture. It's not your drawing skill. Other wise you'd need perform painter or something.

And the person's brain doesn't want to believe it's wrong. So it makes up any excuses for why that's missing. Your brain already does this. Some of what you see is just good guess work by your brain. You aren't actually seeing all of it. Your brain just makes up something that makes the most sense. Which is why you really have to investigate hard into believing other wise. Your brain isn't use to guessing wrong. And the better the caster the stronger the belief.

I think there is a spell about an illusionist bridge that actually discusses this.

Yes, you're playing with a houserule if you believe that this is how all illusion spells operate.

Phantasmal Force creates an illusion in a single creature's head, and the majority of things said in its spell description apply only to that single spell.

Most of the illusion spells that people debate endlessly are not targeted at a creature but instead create an actual optical illusion that doesn't care how many creatures look at it or if no creatures look at it. They create false sensory information and put it out into the environment.

[Dr.Samurai]

But you see a reason to restrain yourself to the idea that illusions aren't capable of anything a computer screen isn't?

The computer screen is the only way I can communicate with you guys on this thread. It's... completely irrelevant. If I hold a picture of a mirror in front of you and you wave your hand in front of that *image*, you won't see a reflection of your hand. The point is that nothing in the description of the spell suggests that the illusion you are creating (the image) has any of the properties of the thing it represents. The notion that because you are making an image of a mirror, it therefore *must* create mirror reflections is completely false.

In other words... there are mirrors (which create mirror reflections) and there are images of mirrors (which do not create mirror reflections). The minor illusion cantrip creates an image of a mirror.

[Potato_Priest]

Quite frankly, it's hilarious how far people go just to rules lawyer a cantrip.

Before you accuse us, take a look at yourself.

[BurgerBeast]

For me, an illusion is created by the person who casts it, and it is a static image. Any attempt to change it would require concentration to make the changes, because it is not reactive on its own. It can't contain AI scripts to respond to the environment independently. Also, it cannot have multiple appearances. The two-dimensional surface of a mirror is different to four different observers at any given instant. You cannot make a picture do that, and you can't make an illusion do that. Beyond the fact that I just don't think an illusion can have four appearances simultaneously, the ability of the human mind to perform the calculations to achieve it even if such illusions were possible would make the task impossible.

Many of the properties that make a mirror a mirror are a consequence of the fact that is physically real and can interact with the environment. An illusion is not physically real.

Also, illusions are not in the mind of the viewer. This is a distinction that was made quite clearly in 2e texts that differentiated the function of psionic illusions from magical illusions. A psionicist needed to invade the minds of all viewers whereas a wizard could simply cast one illusion for all to see. This distinction remains useful. If someone else can see it then it's not in your mind.

Edit: Also, all of this talk about shadows strikes me as mostly irrelevant. Just make an illusion of a shadow as part of the casting.

[Zorku]

You're begging the question. You keep taking your presumed conclusion as an invincibility rather than proving it. Because you can't prove it, because illusion magic isn't real and thus can't behave in any specific set of characteristics other than the ones specifically described by the game rules. The person viewing the illusion has no particular reason to
A) notice a particular detail in passing. That's the whole point of the investigation check, to give a specific examination, like, not only bringing a light source near enough to see how it interacts with the illusion, but actively paying attention to the result of that experiment
or
b) believe immediately that this is an illusion, because how often has someone in this world even seen an illusion? Why wouldn't they assume it's a magic object, or bewitched, or a hallucination?

Little sanity check here: could you actually walk me through that 'begging the question' claim? There's a lot to the post you quoted so I'm not even sure which topic within it is supposed to be inferior even to a circular argument.

And strictly speaking, I don't know that the D&D world knows the difference between illusions and hallucinations.

Realistic shadows

I'm reasonably sure that fantasy logic doesn't consider anything a shadow unless it's a harsh silhouette in a powerful directional light.

All of those texture and lighting details ought to be the same single concept, but they've got different words and probably weren't even concepts that early story tellers knew how to describe (and modern ones don't have anything that really works for a campfire story,) so it's just not the same thing. This is exactly the kind of "these shadows are their own thing because I said so," logic that I absolutely hate to resort to myself, but it's all too clear that that's the kind of assumption the developers were operating with.

Although you've got the kind of rationale that I'd use myself for what a normal human being would notice and what a shadow obviously is, you didn't really get that kind of comprehension of how light interacts with real world surfaces until a century or three after the fuzzy and almost useless line we try to draw for the time period that this is all supposed to take place in, and you can expect another century delay on those ideas really clicking within the fraction of the general public that 'gets it,' but that's far from having everyone on the same page and if you're not going to spell these things out in legal terms you almost have to operate on simpler linguistic tradition, even if anyone that's ever so much as taken an introductory college art course has entirely contradicting sensibilities.

And if I don't want to be generous, I can read the description of phantasmal force and decide that this is only establishing that it's different from normal illusions in that only the one creature sees it and all that other description is just a negation of the "physical interaction reveals it to be an illusion" clause. I'm reasonable enough that I'm not actually going to insist that to be the case, but I've brought it up to demonstrate that this heuristic doesn't fully lock out the "illusions are more in your mind than they are in the real world," interpretation.

If we're looking at it from too modern of a perspective then these things are the smoke and mirrors of stage magicians, but that's both a weird confidence game to set up under someone's nose on the fly, and pre-Scooby Doo era meddling kids didn't really understand that you need a dark room and a mirror to project an image like that, and the actually-voodoo level superstitious types were even more susceptible* to the power of suggestion.

*Well, not exactly more susceptible per se, just more uniform in believing the same kinds of easily exploited delusions. You've still got people today that swear they saw someone transform into a vulture with eyebeams that killed dozens of people in a crowd, while anybody not indoctrinated into that would have seen them striking a silly pose and making some bad animal sounds until just one guy fainted. A fair number of the people indoctrinated into that also see it the latter way, but between that not seeming interesting enough to comment on and all their peers insisting that they must not have seen the same thing there's a lot of negative incentive against calling this out, and again this is too modern and needs too much spelling out. You don't just assume that all the readings are big enough psychology dorks to be able to make reasonable judgement calls about how far you can stretch these concepts... unless you're all over that D20 modern UA where you straight up retrodict the world to make the 'magic' happen right when the caster needs it to.

In a sense it's not even that you're bringing too much modern science into it, but that you're bringing too much modern art into it. This problem shares the same beating heart that the usual objections march under, but it's got a strange field of deflection around it, because we've all been taught that it belongs to this category that's emotionally the opposite of science.

p.s. Hopefully I will remain clear enough with my discussion that everyone can see that I'm not bringing a greater degree of science into this, so much as shedding light on the ways that the current amount doesn't hold up.

You're just reiterating your previous logical fallacy. Illusions aren't real. There's no reason to believe that they would be immediately obvious if they don't interact with light or cast shadows. They're magic. They can work in any possible way so long as the result is they can create things that seem real but offer some method of detection via the investigation check.

Can I make an illusory wall that looks like it was drawn in crayon, and if so, should I expect people to recognize that it doesn't match the stone walls around it?

Some illusions create phantom
images that any creature can see, but the most insidious
illusions plant an image directly in the mind of a creature.[/I]
---Player's Handbook p.203, sidebar: "The Schools of Magic"

I think it's safe to say that Illusions are indeed in the mind of the viewer.

It just became less safe for me. The text is presenting phantom images as a distinct option from images in the minds of creatures.

I also recognize that not every bit of text written about and within a school of magic was cross referenced against all other elements within the same category, and that when they were the cross reference didn't necessarily run in both directions, so I can still leave this one as much up in the air as I please.

Mirrors aren't complicated. They're just a reflective surface

Just for clarity: If you take light and shadows for granted, we know that light passes through illusions (you can see stuff through one, once you realize it's an illusion,) so illusory mirrors don't get to simply reflect light. Most of the people that cry foul of this, are picturing something along the lines of the caster having to think about where the subject is standing, where the mirror is positioned, mentally trace those lines to work out what space should be in the reflection, mentally rotate the parts of this that they can see themselves, and finally fabricate details for any elements that the caster cannot see (and possibly has not yet seen.) For these people the surface of the illusory mirror is not actually reflecting light (because light passes through it,) so this is either a flat image made to look like a mirror, or an exponentially more complicated depth trick, the likes of which ought to only work at a very limited angle.

None of that is satisfying, for lots of reasons, but obviously this doesn't apply if you take a more charlatan approach and declare that the creature looking at the mirror in merely convinced that it is a mirror, and mentally fills in the gaps themselves to make it mentally pass, right up until they focus on it close enough to actually hit the limits of what their own mind will do to try and tell them that this is a mirror. This also doesn't apply in a lot of potential "it's magic" type explanations, but what I really want to drive home is that we don't have enough information to determine exactly what the authors thought, or how thoroughly they even thought about it in the first place. Obviously the reviewed everything a fair deal, but you've got a lot of hazy text that's ripe for self inserting ideas, right up until a bunch of forum goers really tear into it and argue the meanings behind words. Were the developers this critical of the text? Almost certainly not. There's a high probability of them never having discovered how different their concepts of illusions were from each other, and a decent probability of them having left this vague even if they did realize some of those differences.

What we do have, is enough text to convince each other that it's probably this way or that, but that gets really ugly any time two isolated groups come to a conclusion then run into each other and have to call everything back into question.

If the RAW were clear this thread wouldn't exist. Nor the various twitter asks to Sage Advice.

I don't have an issue with the spell being imperfect, either. It's not that it's an imperfect illusion, it's that it's so far from perfect as to be, essentially, useless.

Although you (and I,) apparently walk down a hall seeing the spots that the painters didn't cover thoroughly enough on the last pass and had to go back to do another coat over, where the seams in the base boards are, and the spot where there's apparently a trickle of water down the interior of the wall whenever it rains (but before the paint really bubbles up or starts to chip,) most people don't notice most of that stuff most of the time (and realistically neither of us notice any one detail most of the time, but I guess our minds wander in a way where we particularly recognize a lot of details that others would immediately file away as useless.)

I think about, and classify these kinds of details as a certain kind of thing that stage magicians are really good at getting away with. Most people's eyes simply look somewhere else and blink at certain times, and they just skip right over something that was in plain sight, because they intuited that they were supposed to look somewhere else and pay attention to some other detail. If you act like your eyes work like a video camera then that makes no sense, but our eyes obviously don't work like that. We've got a hideously blurry and damn near colorless snapshot to go off of, with a mind boggling number of shortcuts and best approximation heuristics at at play to create an illusion of consistency and overall flawless perception, when what's really going on is sloppy, bug ridden, and at times so faulty that you can't imagine how someone would think it was functioning properly, yet we all pretty much feel like it's working all of the time until you cut the feed entirely or make it so blurry that not even that little patch in the center is sharp enough to read text (and a lot of people still think it's working normally if you screw up those major parts.)

So instead of eye catching flaws, the question is more "how much does this not look like the most interesting thing I should be paying attention to?" With a little battle mat and some figurines or even a 3d adventure set it's really tempting to act like we're looking at blank rooms that only have crumbled stone where it shows crumbled stone, furniture where we see furniture, and pretty much a perfectly uncluttered, open floorspace with nice flat walls that don't have shelving unless we see it, or really any storage of the thousands of items that large structures are built to house. When you think that of course people would see the human shadow sticking out of a barrel in hard light it's practically a white room, instead of the situation where I've got to isolate that shadow (which a large portion of my brain is busily trying to remove from the equation so I can see "more important" shapes,) from the branches of a nearby tree cast over a bunch of only-kinda-flat paving stones with moss growing up out of the cracks and what was probably horse droppings a week ago all while the shadow is that much blurrier because of the diffuse light cast off of that tailor's storefront and the dozens of other human shadows that are moving about up and down the street.

And if you've decided that the illusionist is basically just constructing whatever shape they can think up then there's a paper thin patch of ground just above the actual ground that masks parts of their shadow so I'm really trying to pick up itty bitty fractions of shadow that catch on tumbleweed fragments that blow about in the wind...

But as you think through all of that it should be clear just how much science we're trying to bring into a game that's basically told you that people will come up and try to poke this with a stick to figure out if it's real or not. In combat you've got a decent fraction of 6 seconds for them to come up and wave a torch around an illusion as part of their investigation check and that's a perfectly reasonable amount of time to take if you want to uncover an illusion without just throwing a handful of pebbles at it. The only problem here is how in the world this could ever be a DC 19 investigation check even with the time constraints, but the game's not made for both the player and DM to have to have 20INT in order to keep track of all the shadows being cast in a verbal and loosely visually described room in order to make the check harder to pull off, and there was any risk of this they especially wouldn't want to force you to figure out how to do that at a middling level if you were better at it than your character.

This stuff abstracts down to an investigation check or physical interaction, and if you can't make up an excuse for how someone failed a check, operating under your personal extrapolation of game principles the devs have tweeted, then you either extrapolated where you shouldn't have or you need to use your imagination in a more creative way.

If you've been reading me well then you'll know that I personally employ a mix of visual illusion and keeping-****-abstract to make this make enough sense to play, without the DM or the players having to needlessly describe minute details of how they've crafted something to fool their opponents.

They must reflect light, or simulate reflecting it (near)perfectly. They must do this from all angles at once like a normal object. They MUST do this, because that is how we see things. Light bounces off objects. If it did not, the object would be a uniform, perfect blackness.

This is an unwarranted assumption, or rather "Is bringing too much science into this."

You know that old school idea of how sight works, where your eyes emit some... thing, and you see it because that thing hit the target? In a world with basilisks and beholders there's good reason to think that that is not how you see things.

Because "Magic"

Why not cut out the entire body of your argument and replace it with this one explanation?

For the most part your reasoning doesn't offer up anything that everyone else can't come up with for themselves. We don't talk about that stuff because we think that the various tweets and text rule it out, and the semantics of casting illusory shadows are "up to the DM."

Now for something gross: Your hypothetical wizard casts minor illusion to make that barrel with the sort-of-works shadows, and subsequently casts silent image to make the same barrel in the same position, but ever so slightly larger/smaller. The guard investigates the barrels and has that little epiphany that this must be an illusion... but the damn thing doesn't seem to have gone faint. There's still clearly a barrel there.

The not-casting-shadows thing was just made up by Crawford at that moment. There's nothing in the actual RAW that says that or even implies it. If you can see it and you don't see through it, and assuming it's not in your head (and it's not. Went over that already) then light is bouncing off of it which means it would have a shadow.

If visual illusions don't cast shadows then they have a 100% reliable way to know if something's an illusion at no cost. Normally it takes an action to inspect which might fail, or you have to get close enough to physically interact with it to determine if it's an illusion.

"Other sensory effect" is in the text, your assumptions are unwarranted, and even a paranoid creature expecting to be tricked doesn't automatically notice the absence of a shadow (for reasons that you probably have to make up on your own.)

Now, "other sensory effects" is a bizarre choice of words if you expect everyone to understand that you mean things like shadows and reflections (does this mean reflections? I really can't tell if it does or does not,) but it's a very sensible phrase if it doesn't actually mean anything and you basically want to force DMs to come up with their own rulings.

Correct. But we are not talking about objects, but about ILLUSIONS. There's a world of difference, and in that world of distance "Magic" is the answer you are looking for.

I am kind of interested in something... If I could make everyone answer this question I feel like it might change the course of these arguments:

Minor illusion doesn't cast shadows.
This doesn't automatically give it away as an illusion.
Can you make this work with personal rulings, and if so, what is the first method that came to mind?

I've kind of smuggled another question into this, but it would take forever to pressure people into actually answering it:

If illusions cannot do ____ what are some practical uses of them?


Most recent answer I've come up with is that minor illusion creates an image of a platonic object, and having been chained up in Plato's cave... well, you know the rest (assuming you even recognize what I'm talking about, in which case you can almost fit this into another idea that's been presented in this thread, except in the way that I broke it just now...)

For me, an illusion is created by the person who casts it, and it is a static image. Any attempt to change it would require concentration to make the changes, because it is not reactive on its own. It can't contain AI scripts to respond to the environment independently.

We've got a dev tweet that's happy to let the hands on a clock face move. This seems to indicate an internal timer suitable for small programmed movements.

Also, illusions are not in the mind of the viewer. This is a distinction that was made quite clearly in 2e texts that differentiated the function of psionic illusions from magical illusions. A psionicist needed to invade the minds of all viewers whereas a wizard could simply cast one illusion for all to see. This distinction remains useful. If someone else can see it then it's not in your mind.

There's also no officially released psionics in 5e as of yet. I like the reasoning, but don't find this to be high enough quality that I would use it myself while trying to convince others (or at least not without additional details to back up the interpretation.)

Edit: Also, all of this talk about shadows strikes me as mostly irrelevant. Just make an illusion of a shadow as part of the casting.

That's up to DM ruling, so sometimes you can't. For what it's worth, I've yet to see a game where the DM insisted that you couldn't produce the image of a shadow.

[BurgerBeast]

We've got a dev tweet that's happy to let the hands on a clock face move. This seems to indicate an internal timer suitable for small programmed movements.

Sorry, I do agree with this. I am differentiating between a programmed set of instructions that are cast at the initial time of the casting and a program that is responsive to external inputs. So I agree that you can make a clock with moving hands, or an illusion of a walking goblin (if the spell persists), for example. But you can't make a responsive illusion unless you (the caster) cause the response. This is why the goblin doesn't automatically react when someone speaks to it, and is also why a mirror can't respond to movements in the room.

There's also no officially released psionics in 5e as of yet. I like the reasoning, but don't find this to be high enough quality that I would use it myself while trying to convince others (or at least not without additional details to back up the interpretation.)

This shouldn't be relevant to the point. My point is, if the illusion is in the room, then it's not happening in the mind of the viewer.

That's up to DM ruling, so sometimes you can't. For what it's worth, I've yet to see a game where the DM insisted that you couldn't produce the image of a shadow.

Agreed.

[ThePolarBear]

Can I make an illusory wall that looks like it was drawn in crayon, and if so, should I expect people to recognize that it doesn't match the stone walls around it?

Saving this quote, will help me with an answer later.

I am kind of interested in something... If I could make everyone answer this question I feel like it might change the course of these arguments:

Minor illusion doesn't cast shadows.
This doesn't automatically give it away as an illusion.
Can you make this work with personal rulings, and if so, what is the first method that came to mind?

I'd like to answer.

It isn't an automatic thing since it doesn't always invalidate the spell when used to project images? Yep,but this doesn't mean that the particular factor cannot be counted as a condition to apply rules on making rolls or not.

The very first method is simply "apply the usual concepts of being a decent DM: Try to be reasonable and bring the most fun for your group". Cheeky, right? But it's an important distinction that has to guide every discussion on forums like these. It's the perspective that has to be brought out as a disclaimer, and i want it to be clear. This usually leads me to consider the other conditions of the situation the illusion is placed in: Are there creatures that might notice? Is a roll necessary? Lighting, believability of the illusion, metal capacity of a creature... everything that i can count and that does not take me a noticeable amount of time to deliberate. Then, make a per-situation ruling.

What is my baseline on judgment of what is created? What the caster expects to have been created - within the limits of the spell. And i try to remember and make sure that any possible problem that might arise is clear to the player, being short in session and eventually have a conversation with him/her after the game/when possible if i have to cut it short.

I apply the "RAW" answer in short: DM adjudicates and narrates the results. In the other post i've already stated part of my thoughts - but remember that Simulacrum is ALSO an illusion - it's way to general of a question to really have a more satisfying answer. It's really a case by case type of scenario.

I've kind of smuggled another question into this, but it would take forever to pressure people into actually answering it:

If illusions cannot do ____ what are some practical uses of them?

Cast wish and create a clone army. Again, Simulacrum is ALSO an illusion.
Basic illusions, for me, are meant to complement something that "is" already, or possible and plausible to be. The little nudge in the right direction. As a general answer.
It's not even a question of being subtle or not - not everything has to be hush hush with illusions for them to be effective. It's the shortcut, the right cog in the machine. And it gets more flexible and less reliant on everything else the "higher" the illusion actually is.

The barrel in the stack, the people you expect, the firework to lift the spirit. The feeling of wonder.

Most recent answer I've come up with is that minor illusion creates an image of a platonic object, and having been chained up in Plato's cave... well, you know the rest (assuming you even recognize what I'm talking about, in which case you can almost fit this into another idea that's been presented in this thread, except in the way that I broke it just now...)

Yes, but i do not even try to go that way. For me it's enough for it to be fun. It doesn't NEED to be rational, even if it helps.
And i do love to have discussion on rules, rulings and whatnot. It's just that magic by itself doesn't really borrows to logical discussions over a certain point, specifically under the effects departments, since sometimes it just isn't consistent even with itself and itìs not possible to come to any resolution since there's not enough material to analyze.

I could make a better point on "why i think that Darkness (the spell) creates a sphere of inky black". This is just not the same.

We've got a dev tweet that's happy to let the hands on a clock face move. This seems to indicate an internal timer suitable for small programmed movements.

I would like to point out that while Mearls is a Dev, it's not an official RAI source. Unless something changed and nobody informed me
In the end, i would be focusing more on the "the clock does can't tick, so the fact that it doesn't move makes it more realistic not less, even if prehaps if someone notices it will go to see what's wrong".

-----

I would like to pose you two questions, referring to the first quote i reserved, above.

Is said wall impossible to have in "real D&D life", or only improbable? For me, if a person think that there's something off is not equivalent to realize that's an illusion, but clearly would change the way said person would react.

Would the illusion of a barrel created with minor illusion in the center of a room, now completely in the dark, be revealed as an illusion should a creature with no ability whatsoever to see it walks over it? For me, no. There was no revelation, no discovery. Should the light come, there would be a very confused creature.

[Vae]

In a game I play one of the players does something similar. He has the Warlock Silent Image at Will Evocation, which he uses to make an illusory inanimate object (eg. a box, barrel or crate) which he hides "inside". Knowing that its an illusion he can see throw it as if it was transparent.

There was also one time where we put a portable hole on a wall which we crowded into while he used silent image on the wall to hide the hole we where in.

[UndeadArcanist]

Keep in mind that for the invisibility trick to work you would have to project two distinct images to each of the viewer's eyes, or they would see it as it is - a cube in the air in front of something else.

[Dalebert]

The trick only works for one person standing in one spot. This is a complex perspective illusion that would need to be different from every single angle and distance of viewing that illusion. Have folks seen that amazing sidewalk art that appears to be a 3D scene but only when looked at from a specific position? It's like that.

I could see a DM allowing it for rule-of-cool, but even within those limitations, like if you want it to appear that way from the doorway of the room as a creature enters, it's extremely complicated. THe guy that does those sidewalk art pieces maps them out mathematically ahead of time to get the perspective right and spends hours to draw them.

Spoiler: 3D sidewalk art

Show

http://www.boredpanda.com/44-amazing-3d-sidewalk-chalk-artworks-by-julian-beever/

[kulosle]

So what use are illusions if they are just static images that can only fool people if the are standing in one particular spot?

[Dalebert]

So what use are illusions if they are just static images that can only fool people if the are standing in one particular spot?

That's not generally the case. We're only referring to the "invisibility" trick that the OP describes. Minor Illusion isn't for making you invisible other than to make an object to hide inside of.

[tieren]

Heres one related to the OP camouflaged blind question:

suppose you have a guard room with a couple of guards in it sitting at a table and playing cards. The door to the room is open and the party wants to sneak past the room unnoticed.

The wizard could cast a minor illusion of an image of the empty hallway in the doorway, and the party could crawl past the door behind the illusion unseen.

If the guards aren't moving around much they probably wouldn't notice the perspective issues.

[Zorku]

Sorry, I do agree with this. I am differentiating between a programmed set of instructions that are cast at the initial time of the casting and a program that is responsive to external inputs. So I agree that you can make a clock with moving hands, or an illusion of a walking goblin (if the spell persists), for example. But you can't make a responsive illusion unless you (the caster) cause the response. This is why the goblin doesn't automatically react when someone speaks to it, and is also why a mirror can't respond to movements in the room.

Since when is time internal? That's like, the MOST external thing.

This shouldn't be relevant to the point. My point is, if the illusion is in the room, then it's not happening in the mind of the viewer.

You brought up psionics from another edition. This edition doesn't contain psionics (yet.) It should not be difficult to understand why I have a hard time utilizing psionics in the logic of how this edition works.

It isn't an automatic thing since it doesn't always invalidate the spell when used to project images? Yep,but this doesn't mean that the particular factor cannot be counted as a condition to apply rules on making rolls or not.

As long as you've got a nice explanation of how someone could possibly fail an ability check for looking to see if an item casts shadows then we'll be good...

The very first method is simply "apply the usual concepts of being a decent DM: Try to be reasonable and bring the most fun for your group". Cheeky, right? But it's an important distinction that has to guide every discussion on forums like these. It's the perspective that has to be brought out as a disclaimer, and i want it to be clear.

I tend not to bring it up because I don't trust relative strangers to recognize that, especially not ones so arbitrary that they argue about how arbitrary their rulings are...

This usually leads me to consider the other conditions of the situation the illusion is placed in: Are there creatures that might notice? Is a roll necessary? Lighting, believability of the illusion, metal capacity of a creature... everything that i can count and that does not take me a noticeable amount of time to deliberate. Then, make a per-situation ruling.

What is my baseline on judgment of what is created? What the caster expects to have been created - within the limits of the spell. And i try to remember and make sure that any possible problem that might arise is clear to the player, being short in session and eventually have a conversation with him/her after the game/when possible if i have to cut it short.

I apply the "RAW" answer in short: DM adjudicates and narrates the results. In the other post i've already stated part of my thoughts - but remember that Simulacrum is ALSO an illusion - it's way to general of a question to really have a more satisfying answer. It's really a case by case type of scenario.

Ok, so at this point you seem to have answered my "what personal rulings do you use to make this work?" question with "I make personal rulings."

Cast wish and create a clone army. Again, Simulacrum is ALSO an illusion.
Basic illusions, for me, are meant to complement something that "is" already, or possible and plausible to be. The little nudge in the right direction. As a general answer.
It's not even a question of being subtle or not - not everything has to be hush hush with illusions for them to be effective. It's the shortcut, the right cog in the machine. And it gets more flexible and less reliant on everything else the "higher" the illusion actually is.

The barrel in the stack, the people you expect, the firework to lift the spirit. The feeling of wonder.

So if I said that "you have entered a 40' by 30' room with an alchemist's workstation in the corner, and little bit of hay on the ground. There is a sconce with a lit torch next to the door you came in through, and another on the opposite wall," and you wish to hide from someone, what sorts of things do you think minor illusion can actually do there, and what sorts of options are opened up if you decide to use silent image instead?

Yes, but i do not even try to go that way. For me it's enough for it to be fun. It doesn't NEED to be rational, even if it helps.
And i do love to have discussion on rules, rulings and whatnot. It's just that magic by itself doesn't really borrows to logical discussions over a certain point, specifically under the effects departments, since sometimes it just isn't consistent even with itself and itìs not possible to come to any resolution since there's not enough material to analyze.

I feel that I have been saying as much for quite some time.

But as for the fun and whimsy emphasis, I greatly prefer that kind of magic in a narrative where the main character(s) do not have access to it. If this were not a game, but rather some novel, I would feel horrendously guilty contriving those Dukes of Hazard moments where it looks like they're going to be hit by a train, and then when we come back the train is much further back and they just scoot by like it was nothing, except that instead of country boys and trains we've got magic, which can do anything so long as I jump through some hoops to make it sound cool.

No, my protagonists need to be bound by rules. They're not Doctor WHO or Q or Doc Brown or Sherlock Holmes, but rather they're the companion, the captain, or the... 80's kid, or sort of Watson (maybe I'm straining the point with this many examples,) that the audience can actually relate to. Those folks know what kinds of tools are available and they experience a great triumph when they use them in a clever way. The omniscient characters get to create weird and troublesome problems just as often as they save the day, because they're not relatable (at least in that respect,) and solving problems with god powers that do anything is only interesting for about as long as some perfectly choreographed machinema of Samus and Master Chief bouncing off of Space Covenant Pirates like pinballs for as long as the animator felt like mapping it out.

Being a badass that only fails when you decide to make them fail isn't quite the force that I think brings anyone to my table, and definitely isn't what keeps them there.

Moreover, I really don't want to surprise my characters by saying "you can't do that" when they've built up some expectations of what a specific spell can do, and didn't think they were making any particular effort to push the limits. I'm fine with scrambling the rules via wild magic or whatnot, but that is imposed on the character either when they choose to be a wild magic sorcerer, or when some magical storm sweeps over the land- not when they move themselves into position to hide and then I tell them that they can not.

I would like to pose you two questions, referring to the first quote i reserved, above.

Is said wall impossible to have in "real D&D life", or only improbable? For me, if a person think that there's something off is not equivalent to realize that's an illusion, but clearly would change the way said person would react.

I had some trouble reading this, but if I understand correctly, you are asking if the crayon-looking wall could actually be a non-illusory wall. It's made of wax that suffered shearing force such that small chunks were caught on paper fibers, which are all real materials that can exist, but my intent (which will help a lot if you understood the part I just said down to the same level that I was picturing it,) was for this to be at a wildly different scale than what wax ought to do against paper fibers. It would still be physically possible for the materials to exist in such a configuration, but there wouldn't be any known means of producing such a thing (and I didn't mention paper so presumably this has to be thick enough to be continuous wax.)

If you were asking about casting the spell, well, so was I. I can't very well say if something is possible when I have just asked others if it is possible.

Would the illusion of a barrel created with minor illusion in the center of a room, now completely in the dark, be revealed as an illusion should a creature with no ability whatsoever to see it walks over it? For me, no. There was no revelation, no discovery. Should the light come, there would be a very confused creature.

I'm generally happier to run it that way, but now you've set yourself in opposition to A LOT of people that insist that any physical interaction reveals these things, no matter how little narrative sense that may make.

Keep in mind that for the invisibility trick to work you would have to project two distinct images to each of the viewer's eyes, or they would see it as it is - a cube in the air in front of something else.

You're bad at illusions if your fake open space "wall" is a perfectly flat and depth-less surface. If you treat it like a ~2 feet deep diorama (adjust depth as appropriate for the circumstances,) then there's a lot more potential for it to blend in, at least well enough that they need to spend an action investigating to realize what's wrong.

Little extra detail: we also use the light scattering in the air for our depth perception. With just one eye people can tell the difference between a normal penny and one that's 10 times the size but far enough away that it has the same apparent size. If you place the normal and giant pennies into a vacuum though, people lose the ability to tell that one isn't normal. In this same way, you could partially convince someone that a wall is further away by blurring some of the fine detail.

That's not generally the case. We're only referring to the "invisibility" trick that the OP describes. Minor Illusion isn't for making you invisible other than to make an object to hide inside of.

Kind of a lot of people keep arguing that the object that you hide in is also only going to fool people that are standing in one spot (or at least, this seems to be a consequence of other behaviors and attributes that they assign to the products of minor illusion.)

[Dalebert]

The wizard could cast a minor illusion of an image of the empty hallway in the doorway, and the party could crawl past the door behind the illusion unseen.

An empty hallway is not an object. Silent Image, on the other hand, includes "or other visible phenomenon" which is pretty inclusive. I'd let him try that but I'd give the guards a perception check to get suspicious and see something as being off. If they happened to be looking at the door at that moment, they would see it shift.

[tieren]

An empty hallway is not an object. Silent Image, on the other hand, includes "or other visible phenomenon" which is pretty inclusive. I'd let him try that but I'd give the guards a perception check to get suspicious and see something as being off. If they happened to be looking at the door at that moment, they would see it shift.

The object the minor illusion creates is a 2d photorealistic poster that looks like the opposite wall and flooring.

its possible someone might notice it isn't quite right, thats what passive perception and investigation checks are for. its not foolproof, its just an option.

[Cybren]

The object the minor illusion creates is a 2d photorealistic poster that looks like the opposite wall and flooring.

its possible someone might notice it isn't quite right, thats what passive perception and investigation checks are for. its not foolproof, its just an option.

no, that's not how the spell works. That's a silly overly broad reading meant to manipulate the rules in the favor of the player, and it's eminently clear what the intentions of the spell are.