If, as Cruel Ultimatum begins to resolve, your opponent's life total is 5 or less and you have two or fewer cards in your library, the game will result in a draw. Your opponent's life total will drop to 0 or less, but Cruel Ultimatum must finish resolving completely before state-based actions are performed. You'll then be forced to draw three cards and fail to draw one. When state-based actions are finally performed, you and your opponent will both lose the game at the same time, which means the game is a draw.