LOL, with Lucas on hardcore this fight was so easy the first time I actually thought it was a miniboss, didn't even come close to dieing with him in 3 playthroughs.
L2P.
Oh, and people are saying that Katarina is extremely overpowered, especially against bosses, so to lose with her...
Hey, nice! I actually just fought that guy today. I too used Kat on hardcore, and tried probably a good 10+ times before I managed to get him. Winning solution was to just focus as much as possible on him and ignore the monster additions.