Essence Thief

If you have less than 3 types of cards in your graveyard, Essence Thief gets +2/+2.
Exile target card from your graveyard: Add {1} to your mana pool.
If you do not use all the mana put in your mana pool by Essence Thief, sacrifice Essence Thief.
"I destroy the dead, and we get energy. It's a win
win."