Actually, if you can get all the Imp gear, cast Imp on somebody and equip them with all of it, you can make one hellova fighter. Can't use magic or their skill, but if you do it to somebody who's skill isn't too useful anyway (like, in my opinion, Cyan or Strago), then you're not losing much and gaining a lot. But I'm sure that's well-known.

Some enemies, you can cast Imp on them and they'll do the exact same attacks as when they were normal. Like the Intangr on Triangle Island, you can cast Imp on him but he'll still use that Fireball spell.