Zavryn, Soul of Vengeance

Haste
{1}{b}{r}: Zavyrn, Soul of Vengeance gains +X/+X until end of turn, where X is equal to the number of creature cards in your graveyard.
You lose X life each time you activate this ability after the first.
Exile a creature from your graveyard: Regenerate Zavryn, Soul of Vengeance.