It's the white Human based one. I was able to beat him with the green deck with some luck but it's probably the strongest deck in the game. Fiend Hunters, Oblivion Rings, Champion of the Parish, Unruly Mobs, and Mentor of the Meek can all be a HUGE pain in the ass.
It's
this one although I could swear he has multiple Champions of the Parish. It would have been a lot less dumb if the burn deck had actual burn spells instead of like freaking Inferno(I'm sorry if i'm spending 5RR I better be casting Apocalypse, Decree of Annhilation or a Dragon).