Rotting Shaman

Evolve. (Whenever a creature enters the battlefield, if it had greater power or toughness than this creature put a +1/+1 counter on this creature.)
Reconstitute {2}{g}. (Pay {2}{g}. Return this creature from your graveyard to the battlefield tapped with a -1/-1 counter on it. -1/-1 counter aren't removed from this creature when it changes zones.)