Guardian Sunmare is a rare Creature — Horse Mount card from Aetherdrift Promos (PDFT), collector number 15p. Current market price: $0.47 (foil $0.48), TCGplayer market prices via Scryfall.
Ward {2} Whenever this creature attacks while saddled, search your library for a nonland permanent card with mana value 3 or less, put it onto the battlefield, then shuffle. Saddle 4