The new spell identification rules are terrible.

[Vaz]

That's no different than someone taking an action to expose it as an illusion by any other means, though.

[Tanarii]

I'm curious why no players thought to toss stuff through the wall of fire and see if it burned? I've had that happen several times with a real wall of fire spell, although not in 5e yet. Same with the other wall spells. Players with no particular rush to do other things with their actions will often loft an arrow at them just in case they aren't real.

Which is one reason why I think it's funny that so many posters here object to monsters ever doing the same thing. In the heat of combat it's a bit iffy, but if there aren't any other available targets ... ?

[ad_hoc]

In the heat of combat it's a bit iffy, but if there aren't any other available targets ... ?

I see what you did there.

[Breashios]

That's no different than someone taking an action to expose it as an illusion by any other means, though.

Except they don't think it is an illusion until the Sorcerer indicates it is (they don't want to take fire damage). Since there is no hint it is an illusion, why would they check if it were. My point was that this spell identification rule has an (possibly) unintended effect of accidentally betraying illusions.

Remember, in my example there are multiple spells that create real walls of fire, including the spell Wall of Fire (maybe that was not clear enough), so the Sorcerer took time to study the effect, thinking about casting Dispel Magic on his next turn. As soon as he successfully make the check though, all that became pointless.

[Jerrykhor]

I also thought it was stupid to require a reaction to identify the spell being cast. Isn't a 'reaction' just an action in response to a trigger, thus require you to actually do something? At the casting of the spell, you either know the spell or you don't, but you haven't done anything.

[Shoulder Crow]

I have played DND for 19 years, sometimes the stories are absolutely amazing, and have played characters that evidently people I have never met have heard of, but I knew that in all honesty unless it says in a spell or ability that "X happens." that it was just whether the dm wanted me to succeed or not and what I rolled and what abilities I have do not really matter.

I love that I have GMs who don't do that. On at least 2 occasions in game we have killed an NPC who was supposed to help us. First was an enemy commander who was gonna turncoat, and the second time it as the King of a country.
I believe in at least one campaign we foiled a BBEG's escape attempt and killed him 3 sessions before the DM thought we would. Not THE BBEG but one of them.

[DivisibleByZero]

At the casting of the spell, you either know the spell or you don't, but you haven't done anything.

And the default is that you don't.
If you potentially want to, it costs your reaction.

[Unoriginal]

In any case, if he is successful, he identifies the spell as major image and confidently barrels through, encouraging his companions to do the same on faith that he knows it will not harm them.

If a Sorcerer looks at a wall of fire, and tries to identify the spell by its effects, the effect the Sorcerer can observe are "there is a wall of fire".

Major Image fake the effects of Wall of Fire. So if you try to identify the spell by its effects, you risk to get it wrong.

The same way that if someone try to figure out who is the person on a painting they think is real with INT (History), they will not look for the details that would show the painting is a fake.

This is why there is a INT(Investigate) or other methods to find the spell you think is X is actually an illusion.

I also thought it was stupid to require a reaction to identify the spell being cast. Isn't a 'reaction' just an action in response to a trigger, thus require you to actually do something? At the casting of the spell, you either know the spell or you don't, but you haven't done anything.

What you're doing is looking at the casting and trying to decode it in the few instants you dispose of.

[Tanarii]

I also thought it was stupid to require a reaction to identify the spell being cast. Isn't a 'reaction' just an action in response to a trigger, thus require you to actually do something? At the casting of the spell, you either know the spell or you don't, but you haven't done anything.

Possible in-game explanation for the abstract rule: It's not a matter of know or not know. It's a mater of deduce from various bits of information, which (depending on DM/players) may not be identical for every casting tradition, magical source, or individual caster, in a short second or three, in the heat of combat ... and cross reference that with what you know or don't know.

In other words, it's a little bit of deduction, and a lot of high pressure recall.

Actions are meta. To paraphrase Gygax on HPs, they're there to make the game work the way the designers want it to work. The game isn't a simulation, it's an abstract game. You can explain the abstraction with an in-game reason (as I just did), but it doesn't have to come from any one posters in-game reason. In other words, the onus isn't on the designers to make the rule fit people's view of what's going on in the world. Especially if it's very easy to make the in-game world explanation fit the abstraction.

[Chaosmancer]

An illusionary flaming wall is just as good as a real one if no one braves running into it...

But this only works if the wall seems like real fire. IF someone walks up to a wall of fire and they don't hear the crackle of flames or feel the heat radiating off it, then players are going to feel a lot more comfortable saying it is an illusion and braving it.

So, Silent Image isn't going to cut it. You at least need a Major Image spell to make that work, and that's a decent sized slot that could get canceled really fast. After all, if the Tielfing Paladin decides that their resistance is enough to take the damage so they can get to the people behind the wall, or someone who doesn't know wall of fire casts create water to try and create a space, then your illusion is broken very quickly.

And, quite honestly, most players I've seen look for solutions. They'll try something to get past that wall of fire if they think it is possible to do, and there are very few illusions that hold up to that level of scrutiny unless you start talking incredibly powerful spells that Mirage Arcane (which is an awesome spell for a Boss BTW

I've actually done it on both sides of the screen.

As a player I've used it multiple times for similar effects, either to scare away dumb monsters who are freaked out that a T-Rex just appeared. Bonfires on things a group is protecting who rush to save it while we get away, etc. Obviously as a player it doesn't matter if I say what the spell is assuming the DM knows how to play illusions and doesn't discount them immediately, but with a bad DM this doesn't work as well.

Like the T-Rex idea, though I'd say there is generally a small window where you have "tough enough to be a threat" "High enough level that casting Major Image is worth it" and "Enemy is weak enough that a T-Rex actually scares it off".

As for the catching things on fire, great idea and I love it, but you could also use a 3rd level spell to actually catch the supplies on fire so that next turn when the goons have thrown something on the fire or grabbed a "flaming" box to save it, it doesn't break the illusion and have them chase you. Touching a major illusion reveals it isn't real, so unless you're casting at the limit of your 120 ft range that is probably only a single turn before one of those enemies reveals the trick.

Still, thanks for giving some actually really useful answers to how you could use illusions in combat.

Has your PC seen a monster be summoned before? Do they have any reason to believe the mage hasn't summoned an actual creature?

If they ignore it completely because they inherently know it's fake without even trying, because how could the NPC fail, then yes, it's bad DMing. If they treat it like the illusion should be treated (they think it's real unless they have reasons not to), but still ignore it because of other reasons (ex: a goblin deciding keeping hitting the mage is better than flee and get picked up by the monster that appeared), then it's normal

To both of these, I have to wonder. If I can get the same answer/result either way, then does the answer/result matter?

If I have my goblin archers continue to hit the man calling forth monsters from the void so he doesn't summon anymore, does it matter if that was my reasoning or if it was because I decided I wasn't going to waste enemy attacks on an illusion? The same exact thing is happening, and the player has no idea why I decided to do what I did unless I decide to tell them the reasoning.


Same with players running into illusions, though I do have a BS story from a few years ago. Player was playing a character with an immense phobia of water, like they went catatonic on boats level of fear. This player knew the DM was using an illusion to make it look like the city was flooding (major meta-game knowledge cause they lived together), so they have their character jump through a wave and break the illusion. That is total BS and still gets my blood boiling, since it turned a very interesting "escape from the city" scenario into a bitter memory, but without the phobia the idea of trying to get thru the water to an exit we could use since our other tricks were failing wasn't necessarily a bad one. Is deciding to brave an obvious danger on the hopes of surviving anyways going to get called out if it turns out the danger was a illusion?

This is the problem I run into, I can get to the same place both reasonably and unreasonably, so does it matter which way I did it?

When it comes to getting advantage on the arcana check for having access certain casting lists, how does magic initiate, ritual caster, bardic spell secrets Eric factor in? Do EK have advantage on identifying all wizard spells or only the ones under fifth level or only certain schools? How about high elves?

It specifies that you get advantage if you are a member of that class. So a person casting hex because of magic initiate does not get advantage to identify warlock spells, but I would say the warlock gets advantage to identify the magic initiate casting hex

If you try to identify the effects of an illusion, you're only seeing the false effects the enemy is showing you.

Ergo, you're not seeing the actual effects of the spell until you can determine the spell is an illusion with an INT(Investigation) or other methods, meaning you can't identify it with INT(Arcana) unless you've seen the casting.

Also something tell me that making enemy casters spend their actions identifying harmless special effects is worthwhile.

Good interpretation, but not what the rules say in the ID section.

Plus, if my math is anywhere close to correct, it's actually way harder to id an illusion by arcana than it is by using that investigation check. Major image is a DC 18 Arcana check, and most enemy spellcasters are going to have a far lower DC than that until you start hitting the end game content.

If a Sorcerer looks at a wall of fire, and tries to identify the spell by its effects, the effect the Sorcerer can observe are "there is a wall of fire".

Major Image fake the effects of Wall of Fire. So if you try to identify the spell by its effects, you risk to get it wrong.

The same way that if someone try to figure out who is the person on a painting they think is real with INT (History), they will not look for the details that would show the painting is a fake.

But, the "effect" of that casting of Major Image is not "create a wall of fire" it is "create something that appears to be a wall of fire unless closely observed"

If it faked the effects of wall of fire it would be much hotter, it would have damaged the floor or walls, it would be longer, there could be dozens of tiny clues that indicate that this isn't a real wall of fire spell.

After all, Detect magic would reveal it to be an illusion, because it is not "faking" the spell Wall of Fire. There is little to no reason to assume that the Arcana check would be fooled either.