There is no way to pull him with mez or pac. It requires a monk, bard or ranger with pre-nerf harmonius arrow. I can't even get singles to clear the room using chanter, magician wizard and 3 T5 mercs.
Alright. camping this guy right now and have been for bout 5ish hours... so far ive gotten him to spawn 3 times. first time he dropped the head feet essence and the mnk bst wep.. and the last two times no essence and the earring. i have confirmed that he does spawn in the room to the west and can spawn at any one of the spots round the tables.. he has spawned in a different spot each time for me. Good Luck hope this helps