Also, I'm not sure I understand how illusions work. So they can damage people, apparently. It's all a little confusing. If there was an example or something somewhere, it would probably make more sense. Can the illusions kill people?
If the target believes it can, yes.
"As far as you can see, the floor ahead of you is clear with no unusual bumps, stone triggers or other such devices that might cause arrows to shoot out of the walls."
But... the character didn't see the illusion of the floor covering the pit with spikes in the bottom.
I think the biggest mistake made in arbitrating illusions is that both the game master and players just assume that, when there is an illusion present, there is a roll involved.
Not in my game. If your not actively trying to spot an illusion or disbelieve one, and say so, your going to be affected just like it's the real thing.
And since the brain is capable of doing some remarkable things to the body, including self inflict wounds, your going to suffer real damage, because your mind has convinced you that it will happen.
"We'll go out through the kitchen!" Tanis Half-Elven
"The accumulated filth of all their sex and murder will foam up about their waists and all the whores and politicians will look up and shout, 'Save us!' And I'll look down, and whisper 'No.' " ~Rorschach