Kalain, Reclusive Painter is a uncommon Legendary Creature — Human Elf Bard card from Adventures in the Forgotten Realms (AFR), collector number 342. Current market price: $0.23 (foil $1.12), TCGplayer market prices via Scryfall.
When Kalain enters, create a Treasure token. (It's an artifact with "{T}, Sacrifice this token: Add one mana of any color.") Other creatures you control enter with an additional +1/+1 counter on them for each mana from a Treasure spent to cast them.