(http://i.imgur.com/Fsa6cc4.png)(http://i.imgur.com/oMGc12s.png)
Giant floating bags of combustible gas with jet engines and cannons... why isn't this a thing already?
To make it more fun (or if nerfage is needed), the on-death clause could be to either release gas (if killed by owner) or explode (if killed by opponent).
(http://i.imgur.com/qWU7KqU.png)