Konami's Yu-Gi-Oh! Duel Monsters is a collection of 21 Holofoil Rare promotional cards released by Konami in two sets of 10 cards and one set of one card: the Yu-Gi-Oh! Monster Capsule: Breed and Battle promotional cards, the Yu-Gi-Oh! Duel Monsters promotional cards, and the Yu-Gi-Oh! Duel Monsters meeting experience card. As these cards all predate the introduction of the Official Card Game and use a different design, they are illegal for tournament play, even though they were printed by Konami.