Harnesser of Storms is a uncommon Creature — Otter Wizard card from Bloomburrow (BLB), collector number 137. Current market price: $0.22 (foil $0.31), TCGplayer market prices via Scryfall.
Whenever you cast a noncreature or Otter spell, you may exile the top card of your library. Until end of turn, you may play that card. This ability triggers only once each turn.