Each Booster Pack contains 10 random cards. Booster Packs offer the chance to acquire cards to strengthen Theme Decks, create new decks, or customize old ones. Dual powers clash! Long years of stability come to an end when Shiny Mega Gardevoir-EX lays siege to the mighty Gear Palace with a host of greedy forces. The Mythical Steam Pokemon Volcanion must wield the dual powers of fire and water to stop them!As the battle rages, Xerneas BREAK and Yveltal BREAK face off in the Pokemon TCG: XY: Steam Siege expansion!