Whirlpool Whelm is a common Instant card from Lorwyn (LRW), collector number 96. Current market price: $0.17 (foil $0.53), TCGplayer market prices via Scryfall.
Clash with an opponent, then return target creature to its owner's hand. If you win, you may put that creature on top of its owner's library instead. (Each clashing player reveals the top card of their library, then puts that card on their choice of the top or bottom. A player wins if their card had a greater mana value.)