Setessan Petitioner is a uncommon Creature — Human Druid card from Theros Beyond Death (THB), collector number 199. Current market price: $0.16 (foil $0.33), TCGplayer market prices via Scryfall.
When this creature enters, you gain life equal to your devotion to green. (Each {G} in the mana costs of permanents you control counts toward your devotion to green.)