Moon Caller

Moon Caller costs {1} more to cast for each creature card in your graveyard.
Whenever Moon Caller attacks, put the top three cards of your library into your graveyard, then put a +1/+1 counter on Moon Caller for each creature card put into your graveyard this way.
{b}{g}{g}, Sacrifice another creature: Return target creature card from your graveyard to your hand.