Walk Among the Graves

Whenever your life total drops to 0 or less you
may reveal the top two cards of your library, if
you do you may gain life equal to one revealed cards converted mana cost and lose life equal to another revealed cards converted mana cost.
Then put both cards into your graveyard. (This ability triggers and resolves before you lose the game, and can be responded to with instants and/or activated or triggered abilities.)