Basically during that battle he's spliced out of his mind on magic superpower heroin so he can teleport, throw fire and lightning at people, freeze people, and lift things like 3000 times his size without batting an eye. He basically made himself powerful enough to kill his perfect weapon, Jack. (although he failed.)

Speaking of him, you wouldn't happen to have some suggestions for AU'ing him, would you? He's basically Giovanni masquerading as a friendly Irish fisherman after his plans to take over everything blew up in his face and he had to fake his own death. And he has a running habit of changing his identity to literally anyone he can get away with being if it helps his goal of power and control and lots of money.