I'm supprised no one posted this way to kill celtus its really this is all you got to do: first run up behind the counter and grab the sniper rifle and then get cletus to pick you up and throw you over the counter (quickly take a photo of him drinking some wine good pp)then run behind those little stands and after every six shots just snip him in the head keep repeting this till he dies then free use to shotguns and sniper rifles. also does the mega blaster never brake/run out of ammo?