Trelasarra, Moon Dancer is a uncommon Legendary Creature — Elf Cleric card from Adventures in the Forgotten Realms (AFR), collector number 346. Current market price: $0.31 (foil $0.37), TCGplayer market prices via Scryfall.
Whenever you gain life, put a +1/+1 counter on Trelasarra and scry 1. (Look at the top card of your library. You may put that card on the bottom.)