Witch-Maw Wurm

When this creature 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.
Whenever you cast a spell, you may put two +1/+1 counters on this creature.
Whenever this creature attacks, it gains trample until end of turn if its power is 10 or greater.