Thurid, Mare of Destiny is a mythic Legendary Creature — Pegasus card from Foundations Jumpstart (J25), collector number 33. Current market price: $4.75, TCGplayer market prices via Scryfall.
Flying, lifelink Whenever you cast a Pegasus, Unicorn, or Horse creature spell, copy it. (The copy becomes a token.) Other Pegasi, Unicorns, and Horses you control get +1/+1.