Lys Alana Scarblade is a uncommon Creature — Elf Assassin card from Eternal Masters (EMA), collector number 95. Current market price: $0.22 (foil $0.25), TCGplayer market prices via Scryfall.
{T}, Discard an Elf card: Target creature gets -X/-X until end of turn, where X is the number of Elves you control.