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! And, as the battle rages, Xerneas BREAK and Yveltal BREAK face-off in the XY-Steam Siege expansion!