It That Never Dies

Unknown, Undying
Compose {x} (If this creature is in your graveyard
you may pay X, where X is this creatures mana cost.
If you do, put this creature on the bottom of your
library. Then, exile cards from the top of your library
until you exile a creature card with unknown. Put
that card onto the battlefield. Then shuffle your
library. Put the exiled cards on the bottom of your
library in a random order.)
Creature cards in you graveyard have Compose {x}.