Tried this guy 3 separate times now and finally developed a strat that may work on the next attempt depending on the DPS. Pin this guy up against a solid wall so he cannot be pushed towards raid. Once mana drain dot hits raid, you are toast, no matter how many clerics you bring along. Once he is pinned, go all out melee and DPS keeping casters and DPS ranged at all times. With luck, you can wack away the mill or so hp's and get your reward. Maybe I will have better luck next time.