This guy spawns in a room with a bunch of mobs with large aggro. He was already up when we came in and killed him. We wailed on him, right over him, and still got three adds from the room. (One roamer and two others that joined in inexplicably).
He spawned repeatedly, and after killing him three times, we left, and he was still up. Just know about the adds - it's a straight up slaughter kinda fight, but the adds were a pain.