Stop That 
Instant
Target player discards a card. Gotcha — If an opponent audibly flicks the cards in their hand, you may say "Gotcha!" When you do, return this card from your graveyard to your hand.
Legality
standardNOT LEGALpioneerNOT LEGALmodernNOT LEGALlegacyNOT LEGALvintageNOT LEGALcommanderNOT LEGAL