Mouseferatu said:
The other potential problem with illusionists is the good ol' Spellcraft check. If you recognize that the guy over there is casting major image, you're probably not going to believe that the ogre who suddenly comes crashing through the door is real.
Sure, a good illusionists tries not to let himself be observed while casting. But let's be honest, that's just not always possible. This is especially true of PC illusionists, who are often reacting, rather than initiating, when it comes to combat.
I've given some serious thought to letting people with both Sleight of hand and Spellcraft "fake" their spells, making the casting of one spell look like another--or at least making it impossible to tell what spell they're casting. (I don't use cross-class skills in my campaign, but if I did, I'd give SoH to the illusionist as a class skill to go along with this.)
Nice idea, but it might be better served to offer it as a feat. That said, the illusionist in the game I run simply starts each combat with
invisibility, then plays the puppetteer to his heart's content. Granted, a few monsters see through this, but it's a simple and viable way to prevent observation 99% of the time--unless, of course, the campaign features as a major component a group of foes who see through invisibility regularly. It works IMC, though, happily for him.
I'm going to rave, now: he's very clever. He casts
invisibility, then conjures a doppelganger of the
enlarged party fighter. He conjures an illusory
wall of fire--barring fire resistant enemies, what sane foe is going to barge through a
wall of fire to see if it's real? No, they go around, ensuring that his fake wall is as "real" as any other. In a world of magic, most folks aren't going to question if the wizard summoned a demon, or only appeared to. The fact is--why risk finding out the hard way!
I intend to work hard to ensure that illusions have their place, with the caveat that enemy spellcasters who have the opportunity to observe you will sometimes see through the deception and react appropriately.