Ambush Commander is a rare Creature — Elf card from Duel Decks: Elves vs. Goblins (DD1), collector number 1. Current market price: — (foil $1.70), TCGplayer market prices via Scryfall.
Forests you control are 1/1 green Elf creatures that are still lands. {1}{G}, Sacrifice an Elf: Target creature gets +3/+3 until end of turn.