In each Pokémon TCG: XY— Steam Siege Elite Trainer Box, you will find:
Gear up for new ways to battle! Take control of Shiny Mega Gardevoir-EX to lay siege upon your enemies. Wield the dual powers of fire and water with the Mythical Steam Pokémon Volcanion. Use dual-type Pokémon to open the way to new, powerful strategies, and battle with the incredible Xerneas BREAK and Yveltal BREAK...all in the Pokémon TCG: XY—Steam Siege expansion!