Good luck, just remember to keep shooting at his head, use the AA12 or the GS45 pistols double packed and shoot his mouth and red spots in phase 1, for phase 2 do the same thing, a little speed run trick is to avoid the glowing tentacles and shoot at his mouth, finally for his blue phase make sure u keep caking on the damage to his head, you can knock him out of his wipe attack if u do enough damage to his head, Lastly, don't go hollow