Your shammies can take a beating from this guy and if you all cast the life siphon the phases move more quickly. When you are in skelly form its pretty hard for thoronja to kill a shaman with a 4k shield and life siphon. Plus you can taunt him back on your tank. I just mouse broadcast and go to town. This is the boss of free loots.

I would say almost any 4shaman +tank group can take this guy out as long as you lay down 4 healing stream totems - they heal more than his ground DoT can do to you in a round.