Soulkeeper Druid

{b}{b}{t}: Sacrifice a creature: Put X +1/+1 counters on Soulkeeper Druid, where X is equal to the sacrificed creature's converted mana cost plus one.
{g}{g}{t}: Remove any number of +1/+1 counters from Soulkeeper Druid, then put that many 1/1 green Saproling creature tokens onto the battlefield.
The dead give him strength, his strength gives them life.