With our current, highly advanced Lag System, I’m surprised it’s not in the game already. Mesmers should be able to play around with time, so I think this sort of ability would fit them the most:
Lag Warp
Freeze the time for 5 seconds, allowing you to move freely, while all of the entities visible shake uncontrollably for no reason.
It’s actually in the game already. You can beta-test this skill in Labirynth (with any class, currently). All the developers need to do, is put it in as an actual skill and make sure that you actually stay in the place you moved to while the Lag Warp was active.
(This topic is meant as a joke, although I would appreciate less laggy labirynths).