Klothys's Design is a uncommon Sorcery card from Theros Beyond Death (THB), collector number 176. Current market price: $0.19 (foil $0.32), TCGplayer market prices via Scryfall.
Creatures you control get +X/+X until end of turn, where X is your devotion to green. (Each {G} in the mana costs of permanents you control counts toward your devotion to green.)