I'm wondering what exactly is the differences between the effects Chameleon, Invisbility, and Shadow. And what is the difference between the Normal and True versions of these effects?
Invisibility is near-perfect concealment (they can still hear you, though). And Stonefrog is correct in that most undead can see right through it. I learned this the hard way
Chameleon is cheaper in that it only offers a % concealment.
Shadow is Chameleon that only works in darkness (read: indoors, not outside during the day)
Normal wears off when you hit someone.
True only wears off when the duration runs out.
Of course, once you hit someone, they will automatically always see you. So the True versions only protect you against his buddies. Still very nice to pick off everyone, one by one, in a crowded room.