The Plague Wurm

The Plague Wurm Enters the battlefield with {x} +1+1 counters on it. Whenever a creature an opponent controls dies,
put a +1+1 counter on The Plague Wurm.
Trample
Infect
Remove a +1+1 counter from The Plague Wurm:
put an poison counter on target opponent
or a -1-1 counter on target creature.