I need help to understand illusions..

[Kerilstrasz]

Assume a Wizard that cast an illusion...
lets say he casts an illusion floor over a pit that seems totally blend in with the surroundings.
Now a player walks near the fake floor without looking for it or stepping on it. What happens? What if he steps on it?
Lets say that that player is searching for traps, so he walks half speed, searching square by square for traps and reaches fake floor. What then?
Another case... he kicks a rock over the floor.. the rock falls through the floor? If yes then does he realizes the "fake floor" instantly?
To sum it up.. what exactly "interaction with the illusion" is?

[Crake]

in your example, the person walking near the floor would get no save, if he happened to fall through the floor, he would likely get a save (not instantly pass it, because there's a multitude of reasons why he may have just fallen through the floor)

The player searching for traps would have to pass a DC 20+spell level (5 for say, illusory wall, which can be used to make fake floors). Success would indicate he finds the trap, and would likely get a save (again, not instant pass, he knows something's wrong, but doesn't know for sure it's an illusory floor). Failure would result in no save, and him possibly falling through the floor.

Finally, kicking a rock onto the floor would grant everyone who saw the rock fall through the floor a save vs the illusion, as they all notice something is amiss.

Note that any character who fails their save can attempt it again by inspecting the illusion for one round (this counts as interacting for the purposes of illusions).

[Galvin]

Anyone who sees and something interact with an illusion gets a save to disbelieve said illusion. In your example, if there were 5 people that saw the rock go through the floor, but only 3 of them are facing the right direction, those three people would get will saves against the DC of the spell, as is always 10+Casting Stat Mod+Spell Level+Any other conditional modifiers. If the character beats the save DC, then the illusion appears to not be there. For example, if one of the three people in the example above succeeded his save, then that one guy would see through the illusion as if it wasn't there, and would see the pit. Whilst the other two guys would see the illusion.

[NeoPhoenix0]

Anyone who sees and something interact with an illusion gets a save to disbelieve said illusion. In your example, if there were 5 people that saw the rock go through the floor, but only 3 of them are facing the right direction, those three people would get will saves against the DC of the spell, as is always 10+Casting Stat Mod+Spell Level+Any other conditional modifiers. If the character beats the save DC, then the illusion appears to not be there. For example, if one of the three people in the example above succeeded his save, then that one guy would see through the illusion as if it wasn't there, and would see the pit. Whilst the other two guys would see the illusion.

There is no facing in D&D. If you want to replicate the chance that a character is facing the right direction you can use a spot check to see if they saw the rock fall into the floor.

[Deophaun]

in your example, the person walking near the floor would get no save, if he happened to fall through the floor, he would likely get a save (not instantly pass it, because there's a multitude of reasons why he may have just fallen through the floor)
Actually, this exact example is called out as being an auto-success in the PHB:

A character faced with proof that an illusion isn’t real needs no saving throw. A character who falls through a section of illusory floor into a pit knows something is amiss, as does one who spends a few rounds poking at the same illusion.
Unless the illusion is being maintained to react to stimuli, then physical interaction (touching it, throwing something at it, etc) is likely to constitute proof and will bypass the need for a save. There are some exceptions. An illusion of a wall of smoke, for example, can have a dozen rocks chucked at it and there won't be an auto-success, because a rock passing through smoke is not proof that the smoke is illusion (it still can qualify as interaction, though, and warrant a save).

[Duke of Urrel]

Assume a Wizard that cast an illusion...
lets say he casts an illusion floor over a pit that seems totally blend in with the surroundings.
Now a player walks near the fake floor without looking for it or stepping on it. What happens? What if he steps on it?

In this first case, there is no interaction with the illusion; therefore, the player gets no Will save. I agree with Crake about this. However, the player should still get a Reflex save to avoid falling in, and the DC is usually 20 for a pit trap, I think.


Lets say that that player is searching for traps, so he walks half speed, searching square by square for traps and reaches fake floor. What then?

As you have seen already, people have differing opinions on what counts as interaction. I consider you to interact with a floor if you actively use Search skill on it. Therefore, a player who starts to search an area with a pit covered by an illusory floor immediately gets a Will save to disbelieve the illusion. The Will save DC is as Galvin described it.

I would also say that a searcher gets a chance to notice the illusory floor as a trap with its own Search DC, which is once again 20. If you search the area around an illusory floor trap and your Search check succeeds, you discover the pit beneath the illusory floor just in time to avoid falling in. Probably a successful Search check means that you discover the pit by poking your foot or perhaps your hand through it, which means that you instantly prove to yourself that the floor over the pit is illusory, without having to make a Will save. I would not grant repeated Will saves against the same illusion for every round of searching, as Crake has proposed. Search checks can be retried, but if you move directly toward a pit trap and your Search check fails even once, you risk falling in before you can make another Search check, and your only hope then is to make a Reflex save.


Another case... he kicks a rock over the floor.. the rock falls through the floor? If yes then does he realizes the "fake floor" instantly?

I agree with Deophaun that kicking a rock that falls right through a floor counts as proof that the floor is not real. If you see something like this happen, you instantly disbelieve in an illusion without having to make a Will save, and so does everybody else who sees the stone disappear through the floor. This is a good trick to remember if you make a Will save to disbelieve in an illusory floor, but your comrades fail their Will saves: Just toss a stone into it, and if they see it, they'll disbelieve the illusion, too.


To sum it up.. what exactly "interaction with the illusion" is?

Answers will vary. If an illusion resembles an object, I always require you to do something in order to study or interact with it. Actively using Search skill near an illusory object usually accomplishes this. If an illusion resembles a creature, it may initiate interaction with you, so that you don't have to take any action in order to interact with it. I usually grant you a Will save as soon as an illusory creature, or a real creature wearing an illusory disguise, starts interacting with you.

As I have already said above, I generally don't grant repeated Will saves every round (unless, for example, you have the Scent ability or an even stronger olfactory sense, or you repeatedly try to make physical contact with an illusory creature whose body is wholly or partly insubstantial). As a dungeon master, I prefer to grant repeated Will saves to disbelieve illusions only if interaction continues for a whole minute or longer, and depending on the nature of the interaction (which may be casual, perfunctory, or intermittent), I may grant repeated Will saves only at intervals of one minute, 10 minutes, whole hours, or even whole days.

[Crake]

Actually, this exact example is called out as being an auto-success in the PHB:

Unless the illusion is being maintained to react to stimuli, then physical interaction (touching it, throwing something at it, etc) is likely to constitute proof and will bypass the need for a save. There are some exceptions. An illusion of a wall of smoke, for example, can have a dozen rocks chucked at it and there won't be an auto-success, because a rock passing through smoke is not proof that the smoke is illusion (it still can qualify as interaction, though, and warrant a save).

The way I see it is that it states that the character "knows something is amiss", meaning the person knows that something is off, but that doesn't mean he knows it's an illusion. With magic, there's so many ways to explain something that merely falling through a floor doesn't necessarily mean auto-pass.

Although that said, you need to draw the line somewhere, because then you could even say that when an illusory iron golem's attacks pass right through you, you could say "oh it's incorporeal somehow" and thus not auto-save.

[Devronq]

Ok i have a question about OPs question. If some of the players tell that illusion is fake and some don't how do you tell them? I mean if you said it out loud then the the players that don't know its an illusion will now so how would you go about this?

[TuggyNE]

Ok i have a question about OPs question. If some of the players tell that illusion is fake and some don't how do you tell them? I mean if you said it out loud then the the players that don't know its an illusion will now so how would you go about this?

Notes! Yes, notes for all!

[Kerilstrasz]

Ok i have a question about OPs question. If some of the players tell that illusion is fake and some don't how do you tell them? I mean if you said it out loud then the the players that don't know its an illusion will now so how would you go about this?

i discourage players ask me (DM) questions about what they should think...
their thoughts supposed to be theirs. Im not there to confirm assumptions. They have to confirm them themselves. If the player though, ask his group "Hey. is this an illusion?" or just tell them he things "that thing" is an illusion then they could search it and then i ll describe what happens..
-Dm: You throw a rock and you can see it fells throw the floor.
-PLayer: So is it a illusion?
-Dm: Don't ask me.. as far as i know it could be a man eating floor.. you have to search it and find out.

Well.. at that point he prolly throw a few more rocks.. if he actively listens i could tell him, he listens the rock collide with ground few feet bellow...
He could poke with a stick... well.. at this point i suppose he has the proof (which was found by him, and not by me telling him "it's illusion")

Anyways... my problem is where i draw the line between "save" & "proof"...
when i ask for a save and when i assume there are evidence that qualify as proof?

[Segev]

If the player is asking you, "Hey, is that an illusion?" based on something he's seen (like a rock falling through the "floor"), I suggest your response should be, "I don't know; roll a Will save to disbelieve." Don't tell him if he succeeded on the save or not, but do tell him if he now can tell that it's definitely an Illusion or if he still think it looks real.

If you want to keep other players from knowing, you can pass him a note. At which point, he can tell the other PCs, and it's up to them whether they trust him or not. If he does tell them it's an illusion, you should immediately let them all roll Will Disbelief saves at +4, per the RAW. Of course, if he was lying, but they believe him, they may be particularly disturbed when even the guy who got in the mid-20s on his save still sees it there...

[Psyren]

Ok i have a question about OPs question. If some of the players tell that illusion is fake and some don't how do you tell them? I mean if you said it out loud then the the players that don't know its an illusion will now so how would you go about this?

Traditionally you would pass notes or pull the players aside. Technology has enabled other ways to transmit selective information however.

[Duke of Urrel]

i discourage players ask me (DM) questions about what they should think...
their thoughts supposed to be theirs. Im not there to confirm assumptions. They have to confirm them themselves. If the player though, ask his group "Hey. is this an illusion?" or just tell them he things "that thing" is an illusion then they could search it and then i ll describe what happens..
-Dm: You throw a rock and you can see it fells throw the floor.
-PLayer: So is it a illusion?
-Dm: Don't ask me.. as far as i know it could be a man eating floor.. you have to search it and find out.

If you disagree that a rock passing right through a floor is proof that it is illusory (as I would,* but if you're the DM, you're the boss), you should at least give the player a Will save to disbelieve the illusion at this point, because this is undeniably interacting with the floor.


If the player is asking you, "Hey, is that an illusion?" based on something he's seen (like a rock falling through the "floor"), I suggest your response should be, "I don't know; roll a Will save to disbelieve." Don't tell him if he succeeded on the save or not, but do tell him if he now can tell that it's definitely an Illusion or if he still think it looks real.

If you want to keep other players from knowing, you can pass him a note. At which point, he can tell the other PCs, and it's up to them whether they trust him or not. If he does tell them it's an illusion, you should immediately let them all roll Will Disbelief saves at +4, per the RAW. Of course, if he was lying, but they believe him, they may be particularly disturbed when even the guy who got in the mid-20s on his save still sees it there...

There's a technique I use called the semi-secret check or save. I tell a player, or maybe all players at once, to roll 20-sided dice, then secretly add the appropriate modifiers only to the roll that actually counts. In the situation above, I'd add only the Will save modifier of the player who was searching around or otherwise interacting with an illusion. If a player's save succeeds, I let him or her know what kind of save it was, but otherwise, I don't tell any player anything, so that the players don't know whether they have rolled failed Will saves or failed Spot or Listen checks. That keeps them guessing!

With Segev and Psyren, I support the idea of passing notes to keep secrets, but in the case of an illusion that one player has already disbelieved, the secret won't be kept for very long, no matter what precautions we take. Merely being told by a trusted ally that something isn't real gives you another Will save at +4, as Segev has rightly pointed out.

It's a house rule of mine that if a player is ignorant or otherwise fooled, he or she must role-play being ignorant or fooled until enlightenment comes, or in this case, until a player either makes a Will save to disbelieve an illusion or sees demonstrative proof that it isn't real.
_____________
*True, if a rock falls right through what looks like a solid floor, the floor may not be an illusion, but what else could it be? Sure, it could be the effect of the Passwall spell, but how likely is that? On the other hand, there are many spells of the Illusion school capable of creating illusory floors; even the Silent Image spell can accomplish this, and this is a first-level spell that is available to several character classes and probably well known. If I saw a rock fall right through a seemingly solid floor, I know what my first guess about the nature of that floor would be. And if a player has a suspicion like this and tests it with a direct action, I'd say that disbelief by demonstration is achieved, so that to this player, the floor doesn't even look solid anymore, but takes on a translucent, false appearance, just as if he or she had made a successful Will save.