Barnt's Assassin

When Barnt's Assassin enters the battlefield, destroy each creature with a
-1/-1 counter on it.
{3}{b}: Put a -1/-1 counter on target creature.
{b}{b}, Sacrifice Barnt's Assassin: Put a -1/-1 counter on target creature.
{b}{b}{b}{b}: Return Barnt's Assassin from
your graveyard to your hand.