VSTAR rule: When your Pokémon VSTAR is Knocked Out, your opponent takes 2 Prize cards.
Ability
:
Star Guardian
During your turn, if your opponent has exactly 1 Prize card remaining, you may choose 1 of your opponent’s Benched Pokémon. They discard that Pokémon and all attached cards. (You can’t use more than 1 VSTAR Power in a game.)