Took quite a lot of time to kill him. Or group had three tanks and quite a lot of healers. After he was at 80%, he became intangible and summoned a shade of one of the Circle of Five. Then we had to kill the shade in time to discover that good ol' Lok was at 100% again. Then when he was at 60%, he summoned another shade. Then when he was at 46%, he summoned another one. Then at 40%, he summoned another one. The last time he summoned a shade and became intangible was at 20%, then we took him down all the way from 100%. Nice necklace, I must say.