Witherscale Wurm (SHM) from Shadowmoor, available at 401 Games Canada.

• Rarity: Rare
• Finish: Normal
• Artist: Thomas M. Baxa
• Card Text:
  Whenever Witherscale Wurm 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 Witherscale Wurm deals damage to an opponent, remove all -1/-1 counters from it.