The Underworld Elderbane

As an additional cost to cast this spell, exile six cards from your graveyard.

Ward—Torment yourself twice (To torment yourself, lose 3 life unless you discard a card or sacrifice a nonland permanent.)

Whenever a player loses life, put two +1/+1 counters on The Underworld Elderbane. Then destroy all other creatures if its power is exactly 20.