Mysterious Pathlighter is a uncommon Creature — Faerie card from Throne of Eldraine (ELD), collector number 22. Current market price: $0.09 (foil $0.15), TCGplayer market prices via Scryfall.
Flying Each creature you control that has an Adventure enters with an additional +1/+1 counter on it. (It doesn't need to have gone on the adventure first.)