Necessary to clear the large room where he is before pulling. Use pet pulls to get mobs and pull into the smaller room you come through to reach him. Make sure you clear them all. Pull mob into the small room and tank/spank as usual. At 75% mob will teleport entire group into the larger room. Each member also gets a "time bomb" DoT placed on them, that detonates a few seconds after teleport. Amount of damage received is tied to how close your character is to other group members. Each member should scatter in a different direction until the DoT passes (probably best to decide who's going where before the pull). No member should head directly south once teleported, as there is an invisible pit there. Regroup in smaller room and continue to fight as normal. Teleports again at 50% and 25% health, just repeat as above.