You can get turn 2 wins if you get unbelievable luck with mutations. I figured it out on another thread, but I think it was something like 2x nova 2x supernova, photon, mutation, twin universe, and hope you get a couple of diving crimson dragons. The best I've ever actually done was 4 turns; I don't think I've ever done it in 3, but I've been close. I'm sure some decks can do 3 turn wins, but you'd need an absolutely perfect draw.