Spawned on the far side of the Invis Bridge, after crossing the bridge I took a left and then the first right. At the fork i took another right and he was spawned in that hallway before the next fork.
He was lvl 54 and sees invis and doesn't summon.
Didnt let him hit me too many times but his max on me was 158 damage and has est. 12-15k Hitpoints