Molideer, Herald of Rot

Whenever a creature dies, put a +1/+1 counter
on target creature you control or put a -1/-1
counter on target creature you don't control.
{b}{g}, {t}: Exile target creature from a graveyard.
Target creature gets +X/+X until end of turn,
where X is the exiled creatures converted mana
cost.
He encourages the cycle with each death he finds.