Vecna, God of Secrets

Lifelink

When a card you control enters the graveyard, you may pay {2}{b} to instead exile it face-down. You
can look at these cards, but other players cannot.

Sacrifce target creature, {p/b}{p/b}: you may cast target face-down card without paying its mana cost, or create a 2/2 black Shadow creature token with deathtouch.