Omnislash

Omnislash deals X damage to each enemy creature and opponent, where X is is the amount of Life you have lost this game.
Limit Break 5 (Rather than cast this card from your hand, you may pay {1}{r/w} and exile it with 5 Limit Counters. Whenever you take damage, remove 1 Limit Counter. When the last is removed, cast this card without paying its mana cost.)