Twin emps strat:

Casters on one side, melee on the other. I take it you are lvl 80?! Your tank being a warrior might hurt, but just use seal of truth with your pallies and righteous fury. The way we do it is make sure each side has full dots on their target, when the twins teleport, its an aggro reset, but the dots will tick over and they will run back to their respective sides, healing a little on the way.

At lvl 80 your caster tank will need constant heals, your melee team shouldn't as the melee boss doesn't hit that hard.

Good luck. And let me know when you get to c'thun :P