Arboreal Alliance is a rare Enchantment card from Tales of Middle-earth Commander (LTC), collector number 497. Current market price: $0.57 (foil $0.40), TCGplayer market prices via Scryfall.
When this enchantment enters, create an X/X green Treefolk creature token. Whenever you attack with one or more Elves, populate. (Create a token that's a copy of a creature token you control.)