Re: Clever use of illusion spell
Illusions I've used in a variety of games over the years, some of which have been mentioned:
The illusion of safe terrain hiding chasms, ditches, rocks, etc. This works well when you're being charged.
The illusion of unsafe terrain so that the enemy has to go around.
The illusion of more men on your side; filling out the ranks, so to speak.
The illusion of a single person/thing guaranteed to put at least a little fear into your opponent (a noted knight, archers, a captive monster, etc)
Distracting illusions - attractive women, lost children, various sights and sounds designed to do nothing but cause the target to turn their head for a phase/round or two.
The illusion of a person being knocked out or killed in combat when in reality they aren't. The bad guy moves to the next target, essentially turning his back to the person he thought he'd just killed. Used a couple of time to good effect.
Illusion to hide or exaggerate wounds, depending on what's needed.
Illusion to hide or exaggerate the quality of goods or animals, to affect price (or, in one case, to avoid theft).
Illusion for purely entertainment purposes, especially in accompaniment of a song or tale (acting out the story as it unfolds). Can be used to acquire sleeping quarters, free meals, etc.
Just off the top o' my head...