Iron-Shield Elf is a uncommon Creature — Elf Warrior card from Lorwyn Eclipsed (ECL), collector number 404. Current market price: $0.40 (foil $0.64), TCGplayer market prices via Scryfall.
Discard a card: This creature gains indestructible until end of turn. Tap it. (Damage and effects that say "destroy" don't destroy it. If its toughness is 0 or less, it still dies.)