So far I have tested 4 DKs rotating death grip + the frost spell that has some range + death coil + that spell that does insta damage to everyone around and has some range to (sorry, very bad remembering names). It's just hilarious when you ping pong someone around.
The entire thing consists in targeting something/someone and spread your toons. Then start the rotation.

First join at BG was like "Oh shit, we have a multiboxer". Then it became "WTF are you doing?". And after that "OMG, the multiboxer is playing ping pong with the horde flag carrier!"


What about this other pew pew that seems a bit more viable than the just for fun DKs setup?

Main = rogue
Followers = 1 x DK and 3x more rogues.
This ensures two things,
1 ) The DK will be always the first target since rogues can vanish or just run around stealthed. He is only needed for the death grip pull, so it's not a big problem anyways.
2 ) When the DK uses his death grip, whatever you death gripped will land just in the middle of 4 rogues for a private endless stunlock session.


Other funny setup would be 2 DKs and 2 elemental shamans with this rotation:
1 ) Death grip + shocks + disease
2 ) Thundestorm + lightning + disease
3 ) Deathgrip + shocks + disease
4 ) Thunderstorm + whatever is left if it's still alive.