Mirage Stadium

This card stays in play when you play it. Discard this card if another Stadium card comes into play.
Whenever a player tries to Retreat a Pokémon during his or her turn, that player flips a coin. If heads, that player retreats that Pokémon (and discards Energy normally). If tails, that Pokémon can't Retreat this turn (the player doesn't discard any Energy).