Currently, I am experimenting with a split dps macro.

What this will do is have each DK target a different arena member.

For example,
DK1 targets arena1
DK2 targets arena2
....etc


Each DK will IWT with his target, rather than assisting. I've found this to be very useful against double healer teams are they can't keep up with the damage and causes mass choas.

After you've done this for a bit, immediately switch targets and smash a low one.