Interaction of Project Image and Invisibility

[GM Abraham]

If an NPC casts both Project Image and Invisibility on himself, how do they interact? Specifically:

a) If the NPC casts Invisibility first and Project Image second, are both the caster and the image invisible?

b) If the NPC casts Project Image first and invisibility second, is the caster invisible but the image visible? (Unless the caster casts invisibility a second time on the image).

c) If the caster casts an offensive spell through the projected image, does the image lose its invisibility? Does the caster? Do both?

Many thanks for any advice! Running a game soon where this very situation is likely to come up.

[bbangerter]

There are no rules that spell out how these interact, so this is really going to come down to a GM call.

Personally I'd rule the spells do not interact with each other at all. That is, the project image is your normal visible version - unless of course you cast invisibility on it (which is allowed as an illusion spell). The fact that spells on the image wouldn't necessarily apply to you, and vice versa, is why I would rule the no interaction between them short of actually casting invisibility specifically on the image.

[Meirril]

The illusion created by Project Image looks like you. You don't get an option to alter the way the image looks (unless you cast an illusion on the projected image). So if you polymorph into an Elf, the illusion looks like the same elf. If you become invisible, it becomes invisible. If you get covered in black tar, so does the image. It requires a move action to get the image to do something that you don't, and that just changes the way it moves to not match yours.

And the spell Invisibility doesn't care if you are using Projected Image or not. If you take an offensive action, you break invisibility. And since your appearance changes, Project Image updates the illusion's appearance.

If you want something to happen to your projected image that doesn't change your actual appearance, you need to cast an illusion school spell on it like the Project Image spell says.