The Cauldron of Eternity

This spell costs {2} less to cast for each creature
card in your graveyard.
Whenever a creature you control dies, put
it on the bottom of its owner's library.
{2}{b}, {t}, Pay 2 life: Return target creature card
from your graveyard to the battlefield. Activate
this ability only any time you could cast a sorcery.
The omnipotent wish granting device. The Holy Grail.