Bokaflod

Gift a Book (You may promise a gift to an opponent when you play this spell. If you do, when this creature enters, that opponent chooses a creature. That creature Liberates a Book from you. If that opponent has no creatures, you may not gift a Book.) Whenever one or more Books enter under an opponent’s control, create a tapped Treasure. (A Treasure is a colorless artifact token with {T}, Sacrifice this artifact: Add 1 mana of any color.)