Massacre Wurm is a mythic Creature — Phyrexian Wurm card from Mirrodin Besieged (MBS), collector number 46. Current market price: $5.50 (foil $19.27), TCGplayer market prices via Scryfall.
When this creature enters, creatures your opponents control get -2/-2 until end of turn. Whenever a creature an opponent controls dies, that player loses 2 life.