Greenmuck, The Fallen

If a -1/-1 counter would be put on a creature an opponent controls, put two -1/-1 counters on
that creature instead.
At the beginning of your upkeep, create a
5/5 black and green Treant creature token for
each creature target opponent controls with a
-1/-1 counter on it.
{2}{b}{g}: Put a -1/-1 counter on target creature.