The ritual Edit
It is a ritual planned by Abe No Seimei to cleanse the world, restore the true body of Abe No Seimei and create a world with peace.
The ritual uses Rokuro to turn into the cataclysm king. As the cataclysm king, Rokuro could not control his actions. The cataclysm king would emit pulses of purifying light that absorb the spell power of weak humans,turning them into stone and leaving behind the humans with strong spell power . The spell power that is accumulated will then be used to resurrect Abe No Seimei.
Abe No Seimei Edit
When resurrected, Abe No Seimei planned to remove all the Yin energy from those who survive. Thus creating a world with peace without anger or sorrow.