I've played my friend and he used his new mono white deck. After some turns, he plays Phyrexian Unlife. This is the first time I've seen it. It says even if his life is 0 he never loses. I'm using black deck at that time and I don't have any sorcery or instants to kill that enchantment. So I just conceded the game. Now I'm still skeptical about that card.
My question is how can you kill your opponent if he has that on the battlefield? I know that there's some other ways to defeat your opponents, but my black deck was built to be aggro/discard deck. So how can a player defeat an opponent without anything to destroy an enchantment?