Slitherwisp is a rare Creature — Elemental Nightmare card from Ikoria: Lair of Behemoths Promos (PIKO), collector number 208p. Current market price: $0.57 (foil $0.87), TCGplayer market prices via Scryfall.
Flash Whenever you cast another spell that has flash, you draw a card and each opponent loses 1 life.