Tarbul's regen is certainly mad. I was chain casting pets the other day, and I messed up, and he interrupted my pet! I ran around the zone, gated, made a new pet, and ran back to him and met him back at the wood bridge. The whole proccess didn't take more then 30 seconds including the pet and the running around buying time to gate. Well when I met him at bridge, he had full hp. The scarry part was he was at 15% or so when I had left him. It'd taken me too many pets to count, and at least 5 minutes to get him down that far. (I didn't time how long though)