Color Stun in ToFS
 

Enchanter color stun doesn't seem to be working on "an ancient mummy" in the tower of frozen shadow. Has happened at least twice to me but not always.

Update - It looks as though the color stun does not take affect if another stun was cast just prior and still in effect.

Update - This appears to be happening in other zones as well, or at least one other zone - Icewell Keep.