Soul-Crystal

When you cast Soul-Crystal, name a creature and pay {x}. Soul-Crystal has {x} Resurgence counters on it. When the named creature is killed, you may cast it from your graveyard by paying {2} and removing a Resurgence counter from Soul-crystal. When Soul-Crystal has no Resurgence counters left, your opponent may add it to his/her hand.
Immortality... for a price.