Wildborn Preserver is a rare Creature — Elf Archer card from Throne of Eldraine (ELD), collector number 375. Current market price: $0.70 (foil $2.36), TCGplayer market prices via Scryfall.
Flash (You may cast this spell any time you could cast an instant.) Reach (This creature can block creatures with flying.) Whenever another non-Human creature you control enters, you may pay {X}. When you do, put X +1/+1 counters on this creature.