What is 'interacting with' an illusion?

[Malin Genie]

As the title asks. More specifically, if an illusion of a wall, or pit, or similar obstacle is produced, does 'looking at it' comprise interaction? Does examining without touching comprise interaction - and if so, how closely does it need to be examined?

Example: A character creates an illusion of spikes rising from the ground to slow pursuers. If a pursuer keeps going and steps on a 'spike', presumably he would get a save for 'interacting' (or would he automatically disbelieve, as his foot just went through the spike!)? What if he stopped at the edge of the spikes and looked at them? Save? Is examining a free, move, attack or full-round action?

Example 2: A character creates the illusion of a wall to deter pursuers. An arrow goes flying through the wall (either from the party or the pursuers.) Save? Automatic disbelief? What if the illusionary wall was a 'grating', with lots of holes?

Thanks for any input - and, as usual, if this topic has been dissected here at ENWorld before, a pointer to past discussion would be just as appreciated!

 

[Seravin]

As the title asks. More specifically, if an illusion of a wall, or pit, or similar obstacle is produced, does 'looking at it' comprise interaction? Does examining without touching comprise interaction - and if so, how closely does it need to be examined?

Hmmm. I just finished reading WoTC's Rules of the Game part 6 and Skip talks about this very subject.

Disbelief: A successful save lets a creature ignore the effect. Spells that allow this kind of saving throw usually are from the illusion school and they don't have any direct effects on creatures or objects, but instead have effect or area entries. Creatures make their disbelief saves upon interacting with the area or effect in some fashion. The rules don't give any guidelines on what kind of interaction is required. As a rule of thumb, a creature interacts with something upon attacking it, studying it, touching it, talking to it, or doing something else that one might do with a real creature or object. Merely looking at something usually doesn't qualify as interaction, but using an action (standard or full-round) to study or identify it does. Sometimes a disbelief save is automatic, such as when a character tries to touch an illusory wall and his hand passes right through it (see page 173 in the Player's Handbook for details).

Example: A character creates an illusion of spikes rising from the ground to slow pursuers. If a pursuer keeps going and steps on a 'spike', presumably he would get a save for 'interacting' (or would he automatically disbelieve, as his foot just went through the spike!)? What if he stopped at the edge of the spikes and looked at them? Save? Is examining a free, move, attack or full-round action?

If you take the above definition, then the save is automatic if the character actually steps on the illusory spikes. As a DM I would 'grant' the character a reflex save to avoid stepping on the spiks though - if successfull, then he doesn't step on the spikes and doesn't know they are illusionary at that point.
Just looking at an illusion isn't generally enough to cause a save. Close examination is either a standard or full-round action. I'm guessing a standard action is enough and that the character can choose to use a full-round action if they care to.

Example 2: A character creates the illusion of a wall to deter pursuers. An arrow goes flying through the wall (either from the party or the pursuers.) Save? Automatic disbelief? What if the illusionary wall was a 'grating', with lots of holes?

By the article above - Automatic save in the first instance. In the second instance I would probably follow the normal rules of interaction. If I was feeling nice I might allow a high DC spot check (DC20 or so).

 

[Malin Genie]

Excellent timing - that must have just gone up on the website!

Thanks for the answers - that pretty much tallies with what I expected.

So new question: if I create an illusory wall, until it is studied (or something is thrown at it or someone touches it,) it will completely conceal those behind it, won't it?

 

[Seravin]

Like from a Silent Image or such? Then yes, the wall will conceal those on either side from each other from sight.

Blindsight, tremorsense, and maybe blindsense should all see through the illusionary wall; but normal vision, low-light vision, and darkvision should all be fooled until the save successfully occurs (I don't have my book in front of me, but I think at that point the glamer becomes a faint outline for those who successfully saved).

 

[Thanee]

Yes. Nasty stuff, if there is a spellcaster beyond the wall using spells with no visual tracing, like enchantments (unlike fireball, which flies from the caster to the target and would come right out of the wall).

Basically an illusion is undistinguishable from the real thing until it is disbelieved, this is includes acting like the real thing (or at least making people think and perceive it so).

Interacting basically means anything, which would provoke a reaction of some sort. Talking, Touching, Fighting, etc. Anything, which would let you observe flaws in the illusion's behaviour or presence.

Bye
Thanee

 

[Vrecknidj]

Can an illusionary wall be created that's one-sided? Here's what I'm getting at. Suppose I'm a nasty wizard and I create a hallway in a dungeon that consists, basically, of one illusionary wall after another, all maybe 10' apart. I make them so that, from the back side, they're simply a faint outline, so that I can see through them. The fools on the other side are now able to be targeted by my line of sight spells.

After the first lightning bolt (or whatever), they realize that the wall is an illusion and go through it, to encounter another wall (and, if I was smart, I also made other illusions, like that of doors on the adjascent walls to this next illusion). While the party is busy, I cook them with a fireball (or whatever). They realize they've been duped again and (as players are wont to do), run through it to the next one. Etc.

Dave

 

[Thanee]

That's not only possible, it's rather automatically the case.

Also see my post above, you don't have to use spells, which are visually traceable.

A successful saving throw against an illusion reveals it to be false, but a figment or phantasm remains as a translucent outline.

And yes, as the creator you automatically disbelief your own illusions, unless you have some serious mental problems.

Bye
Thanee

 

[Ridley's Cohort]

An illusion cannot be one-sided, but it is effectively transparent with respect to line of sight to those who successfully disbelieve. I would also assume that the creator (usually) automatically disbelieves his own illusions.

 

[Hypersmurf]

And yes, as the creator you automatically disbelief your own illusions, unless you have some serious mental problems.

I'm very fond of the Silent Image of a wall of fog when the party is engaged in a long-range archery duel.

It can be communicated to your fellow PCs that it's just an illusion, giving them a good chance at disbelieving it, so they don't suffer any concealment penalties.

But the enemies a hundred feet away aren't interacting with it, so they don't get to see through it...

-Hyp.