Mervak's Call

Create two 2/2 Black Zombie creature tokens.
At the beginning of your end step, create X 2/2 Black Zombie creature tokens, where X is 2 plus the number of black spells you cast this turn. If you control a Mervak Planeswalker, X is 4 plus the number of black spells you cast this turn.
{t}, Sacrifice 10 zombie creatures: Search your library for a Zombie creature card and put it onto the battlefield tapped.