Ravniix, Living Darkness

Lifelink, reach, undying, swampwalk.
Whenever creature dies, put a darkness counter on Raavnix, Living Darkness.
{b}{b}{2}{t}: Put X 1/1 black raven tokens with flying on the battlefield, where X is the amount of darkness counters on Ravniix, Living Darkness.
" I will expose the world to real darkness."