Aside from releasing the base expansion packs, Wizards of the Coast also produced promotional cards, known as Black Star Promos for promotional events, Pokémon-related events, tournaments, merchandise or other events and offers. These are slightly rarer than expansion pack cards and are much more sought after. In total, 53 cards were published over a four-year span. All cards related to Mewtwo Strikes Back have a Kids WB gold foil stamp on them.