Frogkin Kidnapper is a rare Creature — Frog Rogue card from Mystery Booster Playtest Cards 2021 (CMB2), collector number 42. Current market price: $0.51, TCGplayer market prices via Scryfall.
When Frogkin Kidnapper enters, target opponent reveals their hand. Choose a nonland card from it. Ransom that card. (Exile it. Its owner may pay {3} at any time to return it to their hand.)