OK I just left Emperor D'vinn's chest on the floor and ran through the whole zone and did find a spirit. A pop-up message about them being active would be really REALLY nice! *edit* And I still have no idea where it spawns
Just did the same thing in Valdoon's let the chest sit and ran around. Didn't see a spirit, but apparently it escaped.
After each boss kill I get purple text saying saying either no spirit is awakened, or spirit is awakened.. which boss kill wakes the spirit seems to be random.