Mirkwood Trapper is a rare Creature — Elf Scout card from Tales of Middle-earth Commander (LTC), collector number 469. Current market price: $0.44 (foil $0.94), TCGplayer market prices via Scryfall.
Whenever a player attacks you, target attacking creature gets -2/-0 until end of turn. Whenever a player attacks, if they aren't attacking you, that player chooses an attacking creature. It gets +2/+0 until end of turn.