Massacre Wurm

Oracle Text

When Massacre Wurm enters the battlefield, creatures your opponents control get -2/-2 until end of turn.

Whenever a creature an opponent controls dies, that player loses 2 life.

Card Rulings

6/1/2011 If an opponent controls a creature you own, that opponent will lose 2 life when that creature is put into your graveyard from the battlefield.
6/1/2011 If a creature an opponent controls is put into the graveyard from the battlefield at the same time as Massacre Wurm, its last ability will trigger.