The 4th Tank.

[ProfBlake]

snip

Not particularly hard to accomplish if handled with care. You'd pretty much have a Tank whose main focus is actual stance dancing, which, lets be honest here, would be infinitely more interesting than what we currently have, granted that Dark Knight, for example, being the latest tank class to be added to the game, is in fact an interesting class to play as, its final execution is slightly lacking (though that's what balance patches and fixes are for anyway).