Thundertrap Trainer is a rare Creature — Otter Wizard card from Bloomburrow Promos (PBLB), collector number 78p. Current market price: $2.01 (foil $2.14), TCGplayer market prices via Scryfall.
Offspring {4} (You may pay an additional {4} as you cast this spell. If you do, when this creature enters, create a 1/1 token copy of it.) When this creature enters, look at the top four cards of your library. You may reveal a noncreature, nonland card from among them and put it into your hand. Put the rest on the bottom of your library in a random order.