Witherscale Wurm is a rare Creature — Wurm card from Shadowmoor (SHM), collector number 134. Current market price: $0.78 (foil $7.88), TCGplayer market prices via Scryfall.
Whenever this creature blocks or becomes blocked by a creature, that creature gains wither until end of turn. (It deals damage to creatures in the form of -1/-1 counters.) Whenever this creature deals damage to an opponent, remove all -1/-1 counters from it.