Mewtwo (XY Evolutions Prerelease) (51) [XY Promos]

[2] Psychic (20+)
This attack does 20 more damage for each Energy card attached to your opponent's Active Pokemon.

[PP] Barrier
During your opponent's next turn, prevents all effects of attacks, including damage, done to this Pokemon. If 1 of your Pokemon used Barrier during your last turn, this attack can't be used.