[3.5] Fighting an Illusion

[Uncle Pine]

Callisto, Ebreo, Francesco, Gark, Galius, Geralt, Kittan, Sangiorgio, Throgga, Zedd: if you happen to see this thread STAY AWAY. Spoilers are bad. Then again, I guess the title itself could be considered a spoiler...

That said:

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In the next boss battle, the party will face some low level illusionists led by a babau.
I plan to have one of the illusionists concentrate on a Minor Image spell to make the babau look like a pit fiend (by superimposing the image of a pit fiend on it) to frighten the party and buy a couple of rounds while other spellcasters and the babau mess with them. The following problem arises: a pit fiend is Large, while a babau is Medium. If a character that didn't succeed on his Will roll to disbelieve the illusion attacks the "pit fiend" when the babau is in range, how do I determine whether or not he attacked the right square (= the one with the babau in it) instead of an empty one?
Let's say we have this situation:

PF	PF
B	PF
	1	2
3		4

PF = illusory pit fiend; B = babau; 1,2,3,4 = players.
What should I do if 1 tries to attack PF?
What if 3 tries to attack PF with his bow?
What if 4 tries to hit PF with a spell?
I suspect that asking to aim for a square would be too suspicious, and even if I could probably roll a d100 to determine whether or not the characters randomly hit the right square (i.e. 1 would hit on 1-50 and miss on 51-100, 3 would hit on 1-25 and miss on 26-100 as would 4 unless he used aoe spells, while 2 would miss regardless of the roll if he tries to attack in melee), I figured I'd ask to see if someone had better ideas.

[Flickerdart]

It doesn't matter - minor image is a figment, and figments "cannot make something seem to be something else."

[Deophaun]

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0) People only get Will saves if they actively study (standard action) or otherwise interact with the illusion. Upon first contact, there's no reason anyone should get a Will save to disbelieve.

Ask for the attack rolls first.

1) If it's good enough to hit the illusion (which is probably easier to hit than the babau) then he knows it's an illusion now (the standard for proof is falling through an illusory floor; your sword whipping through a pit fiend without a hint of resistance is equivalent) and you can safely ask him what square he attacked.

3&4) Secretly roll their Will saves first. They're now interacting with the illusion, and even if the illusionist makes the pit fiend react to the attacks, that's still cause for a Will save. For ease of use, I'd just have them attack the closest square not affected by cover or concealment.

In truth, this probably shouldn't work anyway. It is, after all, a figment, not a glamer. The proportions of the pit fiend are all wrong for a natural overlay to have any hope of working; it would have to stand awkwardly in order to cover the babau, and the babau would also have to stand relatively still. The illusionist is better off casting minor image in a free square, which has the benefit of sparing the babau any risk if one of the PCs hits the pit fiend with an AoE.

[Fouredged Sword]

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0) People only get Will saves if they actively study (standard action) or otherwise interact with the illusion. Upon first contact, there's no reason anyone should get a Will save to disbelieve.

Ask for the attack rolls first.

1) If it's good enough to hit the illusion (which is probably easier to hit than the babau) then he knows it's an illusion now (the standard for proof is falling through an illusory floor; your sword whipping through a pit fiend without a hint of resistance is equivalent) and you can safely ask him what square he attacked.

3&4) Secretly roll their Will saves first. They're now interacting with the illusion, and even if the illusionist makes the pit fiend react to the attacks, that's still cause for a Will save. For ease of use, I'd just have them attack the closest square not affected by cover or concealment.

In truth, this probably shouldn't work anyway. It is, after all, a figment, not a glamer. The proportions of the pit fiend are all wrong for a natural overlay to have any hope of working; it would have to stand awkwardly in order to cover the babau, and the babau would also have to stand relatively still. The illusionist is better off casting minor image in a free square, which has the benefit of sparing the babau any risk if one of the PCs hits the pit fiend with an AoE.

I agree RAW this doesn't work.

I would allow a save to disbelieve if anyone rolled a knowledge check to ID the "Pit fiend". This would in essence allow anyone with the correct knowledge to get a save immediately.

[Deophaun]

I would allow a save to disbelieve if anyone rolled a knowledge check to ID the "Pit fiend". This would in essence allow anyone with the correct knowledge to get a save immediately.

The problem there is that knowledge checks are not actions, while PCs only get a saving throw when "they study it carefully or interact with it in some fashion," which somewhere was listed as being a standard action. Knowledge checks don't represent anyone sitting back and calmly considering the creature that's trying to kill them: it's instantaneous recognition.

Plus, illusions are already easy to pierce just by accident. They don't need a further nerf. Nor do (creature) knowledge skills need a buff. Putting a minor image in a combat situation will very rapidly lead to its discovery.

[Segev]

I would recommend not making the Babau look like a Pit Fiend, but instead simply making an illusion of a Pit Fiend along with the Babau. That way, you're not violating the Figment rules, and you don't have the questions you're asking come into play. What you might do is have the Minor Illusion appear first as a cloud of smoke out of which emerge the Babau and the Pit Fiend, and see if the party making its saves against the Pit Fiend gets them to ignore the Babau until it starts doing very real damage.

[Flickerdart]

I would recommend not making the Babau look like a Pit Fiend, but instead simply making an illusion of a Pit Fiend along with the Babau. That way, you're not violating the Figment rules, and you don't have the questions you're asking come into play. What you might do is have the Minor Illusion appear first as a cloud of smoke out of which emerge the Babau and the Pit Fiend, and see if the party making its saves against the Pit Fiend gets them to ignore the Babau until it starts doing very real damage.

It would be amusing to employ some kind of minor illusion on the babau (as simple as prestidigitation to make its coloration paler or simply wrong) that would make the party believe the babau is a low-quality illusion, and thus suspect the balor to be more real than it is.

[Ayrynthyn]

It doesn't matter - minor image is a figment, and figments "cannot make something seem to be something else."

QFT.

The problem there is that knowledge checks are not actions, while PCs only get a saving throw when "they study it carefully or interact with it in some fashion," which somewhere was listed as being a standard action. Knowledge checks don't represent anyone sitting back and calmly considering the creature that's trying to kill them: it's instantaneous recognition.

Plus, illusions are already easy to pierce just by accident. They don't need a further nerf. Nor do (creature) knowledge skills need a buff. Putting a minor image in a combat situation will very rapidly lead to its discovery.

Also, good... you could also have one of the illusionists cast invisibility on the Babau assuming none of the party have seen it yet. This way it wouldn't interfere with the figment

as to your question, you're almost looking to replicate the mechanical effects of a 2nd level spell (mirror image) with a level 1 spell. Careful here. Perhaps instead of a 1 in 4 chance of hitting the proper target, it's 1 in 3, or 1 in 2? Either way you should roll randomly and not tip your hand by asking the player which hex

[Segev]

Minor image is a 2nd level spell, too. It includes some sound, unlike the first level silent image.

[Uncle Pine]

It doesn't matter - minor image is a figment, and figments "cannot make something seem to be something else."

While this is true, it doesn't mean that figments can't be used to make the space around something seem to be something else, so similarly to how you can stand in the middle of an hallway and cast a figment to create the image of a wall in front of you or that of an empty hallway, you could use a figment to create the image of a creature around a smaller one. An easier example would be that of someone that need to make a green object look like a red object without painting it: a skilled artist (i.e. an hyperrealist) could put a box on it and paint the box, creating the image of the red object surrounded by everything else that happen to be inside the box.

Ask for the attack rolls first.

1) If it's good enough to hit the illusion (which is probably easier to hit than the babau) then he knows it's an illusion now (the standard for proof is falling through an illusory floor; your sword whipping through a pit fiend without a hint of resistance is equivalent) and you can safely ask him what square he attacked.

3&4) Secretly roll their Will saves first. They're now interacting with the illusion, and even if the illusionist makes the pit fiend react to the attacks, that's still cause for a Will save. For ease of use, I'd just have them attack the closest square not affected by cover or concealment.

How should I determine the AC of an illusion? How would assigning a static AC to an illusion succesfully depict the different capabilities of better illusionists to create better illusions? The idea of having them attack the closest square is good, but what if two squares are at the same distance from the character (as are B and PF from 1 in the example)?
Of course hitting the fake pit fiend would trigger a Will save with the +4 bonus because even if the illusionist tries to have the illusion react to the attack there's a chance that he'll screw up. In the same vein, if a character tries to move through the illusion everyone else would automatically disbelieve the illusion.
EDIT: About the messed proportions between a pit fiend and a babau, see above: since the Image line affects entire cubes of space, one could create the image of a creature surrounded by exactly what it would be there minus other creatures, effectively concealing said creatures from anyone outside the illusion.

as to your question, you're almost looking to replicate the mechanical effects of a 2nd level spell (mirror image) with a level 1 spell. Careful here. Perhaps instead of a 1 in 4 chance of hitting the proper target, it's 1 in 3, or 1 in 2? Either way you should roll randomly and not tip your hand by asking the player which hex

Mirror Image and Minor Image are both 2nd level spells. You're thinking about Silent Image, the 1st level spell. Also, remember that you can totally use lower level spells to completely replicate higher level spells: Ghost Sound + Silent Image replicate Minor Image and Alter Self dwarfs many higher level buffs.

[Der_DWSage]

For the AC question-I'd leave it at 8+Mage's casting stat+1/2 their level, rounded down. (Base 10, -2 for size) Makes it incredibly easy to hit, and when hit, disbelieved.

Also...not to sound like a shill, but maybe you should consider replacing the mages with a Spheres of Power Illusionist, or just using their mechanics for the fight? (It's Pathfinder, but easily enough backported) It'd answer most of your problems pretty neatly, and would actually let the 'Pit Fiend' attack opponents, making it seem like a much more potent combatant...until will saves are made.

I'm assuming these are 3rd level Wizards or 4th level Sorcerers, so Illusion/Touch/Touch/Sound fits pretty easily into their talents. It'd give the illusion the same AC I suggested above, and the Pit Fiend would cause Caster Level+Casting Modifier nonlethal damage to those it hits...if they fail the will save to disbelieve.

I'll also second the 'Disguise a Babau as an illusion instead' trick. Maybe have two or three actual illusions that look like him as well, just to make it a triple-bluff.

[Deophaun]

EDIT: About the messed proportions between a pit fiend and a babau, see above: since the Image line affects entire cubes of space, one could create the image of a creature surrounded by exactly what it would be there minus other creatures, effectively concealing said creatures from anyone outside the illusion.

Not really.

Hyperrealists (and let's face it, a fake 2D image or very shallow 3D one is the only way a figment can make something disappear) rely on the audience viewing the work from a particular angle. If they're off by only a few degrees, the image appears flat and fake. Off by a few more, and it's a distorted mess. From where the PCs are in your chart, they'd notice immediately that they were looking at something like a painting or a theater screen. they might not know it's an illusion, but they won't need a save to recognize it's not a real pit fiend, either.

The only way it could somehow work is if you were trying to get the full, 3D illusion of the pit fiend to completely envelop the babau, much like you would do if you were trying to create an illusion of a boulder to hide within. The problem there is that something the size of a babau, even as spindly as its body is, is not neatly covered by a pit fiend. It's limbs will stick out unless the pit fiend is standing in a closed, unstable stance. You could probably get away with a hezrou, which has much stockier legs.

For the sake of discussion, let's allow that these creatures don't just all emerge off an assembly line, and that there's wide variation. So, we've got a big-boned pit fiend on our hand. What's his AC? We start at 10, and as it's an illusion of a large creature, we say it's large (-1). It has no actual armor. No natural armor either. No deflection bonus, or sacred or profane. The only thing it has is the equivalent of its Dexterity (+8), assuming we're going to make it behave like a pit fiend. Now, this is very iffy, because of course it doesn't have the same Dexterity as a real pit fiend; it's a puppet controlled by a mage. It simply won't react as well. Unfortunately, for this we don't really need to consider Dexterity for a simple reason: it cannot move.

I don't mean that it can't take a five foot step. I mean it needs to be frozen in place, almost like a statue, or the babau underneath is revealed. It's Dexterity for this purpose is 0 (-5).

In the end, its AC is 4.

Don't be surprised at that. You are using a spell for something it's simply not designed to do, and finding loopholes to make it do things it is forbidden from doing entirely. Of course the results will be terrible.

[Uncle Pine]

Also...not to sound like a shill, but maybe you should consider replacing the mages with a Spheres of Power Illusionist, or just using their mechanics for the fight? (It's Pathfinder, but easily enough backported) It'd answer most of your problems pretty neatly, and would actually let the 'Pit Fiend' attack opponents, making it seem like a much more potent combatant...until will saves are made.
[...]
I'll also second the 'Disguise a Babau as an illusion instead' trick. Maybe have two or three actual illusions that look like him as well, just to make it a triple-bluff.

I've read a lot of good things about SoP before, but I'm still reluctant to draw rules from other editions for the same reason that "stretching the rules is fun and all, but making up new ones on the fly is kind of a dirty move".

The only way it could somehow work is if you were trying to get the full, 3D illusion of the pit fiend surrounded by nothing else to completely envelop the babau, much like you would do if you were trying to create an illusion of a boulder to hide within.

Edited for the sake of clarification.

Moving on the next part:

For the sake of discussion, let's allow that these creatures don't just all emerge off an assembly line, and that there's wide variation. So, we've got a big-boned pit fiend on our hand. What's his AC? We start at 10, and as it's an illusion of a large creature, we say it's large (-1). It has no actual armor. No natural armor either. No deflection bonus, or sacred or profane. The only thing it has is the equivalent of its Dexterity (+8), assuming we're going to make it behave like a pit fiend. Now, this is very iffy, because of course it doesn't have the same Dexterity as a real pit fiend; it's a puppet controlled by a mage. It simply won't react as well. Unfortunately, for this we don't really need to consider Dexterity for a simple reason: it cannot move.

I don't mean that it can't take a five foot step. I mean it needs to be frozen in place, almost like a statue, or the babau underneath is revealed. It's Dexterity for this purpose is 0 (-5).

In the end, its AC is 4.

Don't be surprised at that. You are using a spell for something it's simply not designed to do, and finding loopholes to make it do things it is forbidden from doing entirely. Of course the results will be terrible.

That actually sounds right, except that all objects also suffer a -2 penalty to AC, so the final AC would be 2. I also recognize I was biased toward making the whole thing way more effective than it should be. After all unless he prepares an action to do so the illusionist can only move the pit fiend during his turn, so it's natural that the AC to hit it will be extremely low.

Now the AC problem is solved, but assuming that hitting the illusion isn't enough to automatically disbelieve it (but still grants the chance to do so with +4) because maybe the character hit it from a weird angle, or because it's a balor so it might be using weird magic or for whatever reason, how should I determine whether or not the character has a chance to hit the babau because he attacked the square it's standing in?

[Deophaun]

how should I determine whether or not the character has a chance to hit the babau because he attacked the square it's standing in?

I'll go back to my original suggestion: Don't roll. Just assume they are attacking the closest unobstructed square (squares on an angle are further away). If you have two front liners lined up between the pit fiend and an archer, the closest unobstructed square would be 5' off the ground, and so wouldn't threaten to hit the babau at all. It's not going to be an issue for long and I doubt 95% of players would have an issue with it (and the 5% would have an issue with any method anyway).

Edit: Now that I think about it, the reason they probably never bothered trying to make rules for AC is because the Will save for interaction can be interpreted as the figment's AC: it shows how skilled of a puppeteer the mage is to make it avoid the hit. With that in mind, under normal circumstances, I'd say just go with the Will save and don't worry about AC at all (it would be really slick if you could convert their attack roll to their save without asking). However, here, I would just use the AC hit as proof, because of that whole "can't move" thing.

You're being bad, take the penalty.

[Uncle Pine]

I'll go back to my original suggestion: Don't roll. Just assume they are attacking the closest unobstructed square (squares on an angle are further away). If you have two front liners lined up between the pit fiend and an archer, the closest unobstructed square would be 5' off the ground, and so wouldn't threaten to hit the babau at all. It's not going to be an issue for long and I doubt 95% of players would have an issue with it (and the 5% would have an issue with any method anyway).

In the end, I'll go with this method. Then, as soon as the last illusionist is slain and the session is over, I'll have a talk with the group to fill once and for all the "grey areas" of the Illusion rules.

Thank you all for your input!