Elvish Branchbender is a common Creature — Elf Druid card from Duel Decks: Elves vs. Inventors (DDU), collector number 6. Current market price: $0.30, TCGplayer market prices via Scryfall.
{T}: Until end of turn, target Forest becomes an X/X Treefolk creature in addition to its other types, where X is the number of Elves you control.