A/N: I wrote this out of boredom thinking someone will use it.
Gods fell in a war, their enemy is one, the will of the world was left to recover and new races were born, that monster was left sealed and one day it will return.
The gods hid in their dimensions to recover where their myth is recorded in akasha, their own cosmologies or realities.
Many years later humans rose from the lands and lived for many years, until beings from another dimension invaded and secretly killed humans from the mirror dimensions diminishing their souls before their entire existence is erased from the records of akasha, thus their any memories and relevance will be rewritten to have not lived or exist.
Later on in the modern age, only a few humans have the capability to fight against the invaders and in history, those who survived the hunt for their souls, becoming aware of the invaders and able to harness the power of the enemies they defeated like campione.
Later a few gods managed to recover a bit of their power and because of the damage given by the invaders to the world, mana have sunk into the core of the world leaving the will of the world to store it.
When the humans joined by gods incarnate who used the vessel of suitable bodies to descend to the world are in the middle of the last fight. The enemy that cast an illusion to a terrifying degree managing to recreate the strongest being that made the gods fear in its weakest.
Although the winners are determined in this battle, the emergence of this great enemy who once made gods fall to their slumber has awoken and slaughtered several vessels before being destroyed from the suicidal attack of many vessels and humans.
Ultimately the humans and the gods managed to repel the enemy and close the gates, the fear that once shiver the spines of God's will return.
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Writing this so someone can use it for their novel and one day read it for fun.
Inspiration taken: Campione heretic gods, shokugan no Shana crimson denizen/crimson lord, fate grand order sefar.