Undead, Mocker of Death

Zombies you control get +1/+1 for each creature in your graveyard.
{1}{u}{u}, Sacrifice a creature; Zombies you control get hexproof until end of turn.
{1}{b}{b}, Exile target creature in a graveyard; Create a 2/2 black zombie creature token, then target creature gets -1/-1 for each zombie you control.