It would have to be like the factions. You pick a class and your locked into that class for the event. The rewards would be tough though, too many people would start it but do nothing and reap the rewards of their class victory. Ok, just thought of this. It might be lame but have the Tower decked out with banners and such of the winning class, have all the NPCs be dressed as the winning class, and have some Tower dialogue from them talking up the winning class. Just to rub it in.