Deal with the Devil

Create a Y/Y black Demon creature token with flying, trample, and indestructible, where Y is three times X.
At the beginning of your upkeep, if Deal with the Devil is in your graveyard, you lose 3 life.
Flashback - {x}{b}{b}, Pay 3 life, Sacrifice 3 creatures, Discard 3 cards. (You may cast this card from your graveyard for its flashback cost. Then exile it.)