Liliana's Curse

Liliana's Curse enters the battlefield with 7 crow counters on it. Whenever a player casts a black spell remove a crow counter from Liliana's curse. If you do, target opponent loses 1 life.
{2}{b}{b}, Exile Liliana's Curse: Destroy all creatures. Activate this ability only if Liliana's Curse has no crow counters on it or if you control a Liliana planeswalker.