Harbinger of the Tides is a rare Creature — Merfolk Wizard card from Duel Decks: Merfolk vs. Goblins (DDT), collector number 7. Current market price: $0.63, TCGplayer market prices via Scryfall.
You may cast this spell as though it had flash if you pay {2} more to cast it. (You may cast it any time you could cast an instant.) When this creature enters, you may return target tapped creature an opponent controls to its owner's hand.