What worked for me, and keep in mind I'm bad at this, was run past him into the hall just befoire the bats.....don't aggro the bats, let the adds come to you. Granted I'm using a Paladin to tank, but the adds aren't really what you're complaing about right? Frost aura, should be about the same as your frost totem. Once the adds are down, he comes to you. Chain heal one 1 shaman, while the other kill. It's really easy if the adds are out of the way, any running loose is where I have problems. His frost attacks imo are really weak. After the adds, he's a tank and spank.