Beseech the Mirror

Mana Cost: {1}{B}{B}{B}
Total Cost: 4
Type: Sorcery
Description: Bargain (You may sacrifice an artifact, enchantment, or token as you cast this spell.)
Search your library for a card, exile it face down, then shuffle. If this spell was bargained, you may cast the exiled card without paying its mana cost if that spell’s mana value is 4 or less. Put the exiled card into your hand if it wasn’t cast this way.
Colors: B