Magcargo-GX

Once during your turn (before your attack), you may discard the top card of your deck. If it's a basic Energy card, attach it to 1 of your Pokémon.

Discard any amount of basic Energy from this Pokémon. This attack does 50 more damage for each card you discarded in this way.

Discard the top 5 cards of your opponent's deck. (You can't use more than 1 GX attack in a game.)

Pokémon-GX rule: When your Pokémon-GX is Knocked Out, your opponent takes 2 Prize cards.