Ambitious Necromancer

Entomb X, Sacrifice X creatures (Sacrifice X creatures: Look at the top X cards of your library. You may choose a creature card from among them and put it into your graveyard. Put the rest on the bottom of your library in any order.)
When Ambitious Necromancer entombs a creature, put it onto the battlefield under your control, put Y +1/+1 counters on it, where Y is the number of cards put into your graveyard from your library this turn.