The Clow Deck
Strange cards and a strange box, the things pictured on the cards are brought to life when their cards are drawn randomly from the deck and their names are called. All but three of them seem to have jewels on them somewhere, and the party knows that those jewels are the means of returning the creatures to their card states. Deactivated cards move to the hand of their deactivator. How the card creatures can be controlled remains unknown.