Chorus of the Conclave is a rare Legendary Creature — Dryad card from Ravnica: City of Guilds (RAV), collector number 195. Current market price: $0.50 (foil $2.54), TCGplayer market prices via Scryfall.
Forestwalk (This creature can't be blocked as long as defending player controls a Forest.) As an additional cost to cast creature spells, you may pay any amount of mana. If you do, that creature enters with that many additional +1/+1 counters on it.