I see that the thief has unique dodge animation and sound. So I think rest of the classes deserve this also, a few ideas:
-mesmer: turns into a cloud of butterflies(like in alice madness returns)
-necro: some dark cloud effect, or something to do with souls
-guardian: insert your idea here
-warrior: insert your idea here
-elementalist: mist form
-engineer: insert your idea here
ranger: cloud of leaves
What do you think?:)