I just have 2 shamans drop earth elemental, since they are immune to the poison, and novas, and aren't targets for the arcane bombs. They hold aggro pretty well since you don't do a ton of damage with all the moving. I run 5 shamans, so I just have all of them GW and run away during the bombs and pursuit parts. Drop a nature resist totem to boot and most of it is pretty simple.

Anyway good luck