Erhnam Djinn is a uncommon Creature — Djinn card from Beatdown Box Set (BTD), collector number 54. Current market price: — (foil $0.49), TCGplayer market prices via Scryfall.
At the beginning of your upkeep, target non-Wall creature an opponent controls gains forestwalk until your next upkeep. (It can't be blocked as long as defending player controls a Forest.)