The Spirit Realm

is a good place for the info on spells and effects of this mob. basically he has an ae stun. i did him with 4-5 groups, but we had 3-4 shaman present for it, and poped him back to back to back. not sure if this was fixed but if your sitting when the stun goes off, you get the symbol, but not the stun efffect, so if you have 2 healers, 1 should sit (or atleast time the procs so they sit just pior) so they can spot the tank while the other healer is interupted...but that might have been a bug and fixed not sure.