What actual effect does this have?

[SangoProduction]

You may disguise a target as something larger than itself (up to your maximum illusion size) but can only make something appear to be one size smaller than it actually is.

This is part of the illusion sphere's description, and has interesting implications. So, are any of the size modifiers to be hit applied, until they disbelieve it? Obviously, hitting due to the size modifier (in the case of being larger) would likely provoke a will save to disbelieve.
But what would be other not so obvious consequences of this?

[Psyren]

The way I read it, you can disguise say a dog as an elephant, but not as an ant. Not sure if that helps.

[SangoProduction]

The way I read it, you can disguise say a dog as an elephant, but not as an ant. Not sure if that helps.

Well, yeah. But what actual effect would disguising yourself as an elephant do for you?

[Psyren]

Well, yeah. But what actual effect would disguising yourself as an elephant do for you?

As with most illusions, the effects depend heavily on the specific circumstances and what you're trying to accomplish by doing it. It's not something that can really be answered in a vacuum.

Assuming your illusion isn't so incredible they auto-disbelieve (say, you disguise yourself as an elephant but forget to disguise the horse you're riding) - and assuming they fail their save to disbelief, if they get one - then they think you're an elephant. What an observer does with that information depends on them. If they saw you cast the ability, they might think you actually polymorphed into one. If they didn't and they're afraid of elephants, they might hide. If they hate elephants with a burning passion they may attack you. If they feel amorous towards elephants you may be propositioned... and so on.

[SangoProduction]

Say they attack the disguised form of you being an elephant, but are actually a gnome. Chances are, hitting center of mass of the elephant wouldn't work to hit the gnome, right? And since it's a disguise, and not a necessarily static image, could you get a bluff check to play along and not let them get their disbelief?

[Psyren]

Say they attack the disguised form of you being an elephant, but are actually a gnome. Chances are, hitting center of mass of the elephant wouldn't work to hit the gnome, right? And since it's a disguise, and not a necessarily static image, could you get a bluff check to play along and not let them get their disbelief?

I can't speak to 3.5, but in Pathfinder, attacking the illusion would count as interaction and automatically trigger a save vs. disbelief. In addition, if you fail to make the illusion react convincingly to some attacks (say, a sword or arrow or fireball bead passes harmlessly through it) then that might count as proof that it is an illusion and they wouldn't need to save at all.

What happens then might depend on the kind of illusion it is. Does that sphere move have a descriptor on it?

[SangoProduction]

I'llusion (Glamour)

[el minster]

I can't speak to 3.5, but in Pathfinder, attacking the illusion would count as interaction and automatically trigger a save vs. disbelief. In addition, if you fail to make the illusion react convincingly to some attacks (say, a sword or arrow or fireball bead passes harmlessly through it) then that might count as proof that it is an illusion and they wouldn't need to save at all.

What happens then might depend on the kind of illusion it is. Does that sphere move have a descriptor on it?

you get the save in 3.5 as well

[Psyren]

A glamer that can be disbelieved effectively ends with respect to the person who disbelieved it, but others (who failed their save) may still be fooled. The ones who successfully saw through it can communicate this fact to others though (giving them a new save with a bonus), or definitively prove it in some way (like grappling the gnome residing "inside" the elephant.)

[Zombimode]

Say they attack the disguised form of you being an elephant, but are actually a gnome. Chances are, hitting center of mass of the elephant wouldn't work to hit the gnome, right? And since it's a disguise, and not a necessarily static image, could you get a bluff check to play along and not let them get their disbelief?

As already mentioned attacking is interacting and thus would prompt a save to disbelieve (after the interaction!). Per RAW the attack itself won't be modified. If they hit the "elephant" they just happen to hit your actual location.

Now, you could argue that an illusion of a larger creature makes it more likely that an attack would strike at a space where the traget does not physically exists. As a DM I could myself see to grant a, say, 20% miss chance due to a "displacement" (NOT concealment!) effect under the right circumstances.

[Powerdork]

Larger creatures take up more space, and illusions of them must as well to be convincing in any way.

If you're making an attack against a creature you can't see, you need to guess the space they're in correctly to have a chance of hitting them (see invisibility, snowstorms, etc.).

The difference between making an illusion of a large creature around yourself and mirror image or displacement is that mirror image fits comfortably in your space.

The precedent for illusions having an AC is in the Magic chapter's description of figments.


Here's a quote from the magic chapter to help everyone internalize the workings of illusions.


Saving Throws and Illusions (Disbelief): Creatures encountering an illusion usually do not receive saving throws to recognize it as illusory until they study it carefully or interact with it in some fashion.
A successful saving throw against an illusion reveals it to be false, but a figment or phantasm remains as a translucent outline.
A failed saving throw indicates that a character fails to notice something is amiss. A character faced with proof that an illusion isn’t real needs no saving throw. If any viewer successfully disbelieves an illusion and communicates this fact to others, each such viewer gains a saving throw with a +4 bonus.

So the understanding that it's an elephant is automatic until someone's given reason to doubt it, in which case it's a Will save, and if they fail that save, they don't notice anything amiss; only genuine proof that it's illusory counters the illusion outright, and sharing your knowledge grants everyone a saving throw with a bonus. The elephant isn't at all visible when you disbelieve it, in case it matters for playing out reactions.

[Doctor Despair]

So the understanding that it's an elephant is automatic until someone's given reason to doubt it, in which case it's a Will save, and if they fail that save, they don't notice anything amiss; only genuine proof that it's illusory counters the illusion outright, and sharing your knowledge grants everyone a saving throw with a bonus. The elephant isn't at all visible when you disbelieve it, in case it matters for playing out reactions.

So if you can create a realistic illusion in combat (e.g. "Greater Cube of Defensive Gelatin!" cast on an ally in melee), folks shouldn't automatically succeed on their save, and if they fail, they would no longer be able to see your ally. That would grant total concealment, right, as you'd clearly have line of effect, but possibly not line of sight? Although that particular illusion probably wouldn't allow your ally to attack in melee without automatically spoiling the illusion for anyone that can see the attack.

[Hawk12192]

Generally the only time you would need to worry about size is to make your illusion more believable. I.e. don't make a tiny elephant. Other than that, in terms of other effects, not a whole lot changes in terms of interactions and stuff.