the fire throw is painfully slow and the vacuum at worst just pulls and does nothing. btw when he vacuums you throw stuff at him, and he gets sick or some crap, but it doesnt matter, cuz the tactic is the same, just dps him for 2 thousand years
I just kited the weapons and hid behind the pillars. What you are supposed to do though is throw a boulder from the ground at him when he does his suction/vacuum/eating thing. That will knockdown & stun him.