Damian Voltaris Dragoneer.
The man who became the demon king. He was born as a feeble and weak dark dragon. He is disdained even among the dragon race for his weak strength until he discovered his real power. The power to devour and gain power. With that he defeated opponents, devoured his enemies and grew strong enough to become the greatest calamity in the world. He became the demonic dragon of the world.
But no one knew he has a truth hidden deeply. He is a reincarnated man. Using that knowledge he brought from another world, he climbed the power ladder until he reached the top becoming the demon king uniting all races across the planet.
But the Gods of the world are not happy at all, their faith dwindled with the rise of the demonic dragon. No matter how many heros appeared, they're either defeated or used as materials for the Demon King's strange experiments. Finally they had enough, the Gods made a long term plan and inflitrated deep into the Demon King's ranks.
They wanted to slay the demon king at the moment of his most vulnerability. Naturally Damian won't take this lightly, he banned all religions and further starved gods of their power of faith, he also inflicted a curse on the doctrines of these gods. Whoever prays to the God and got their attention will in return become cursed, their bodies will become weak and their lineage suffers from the dark power of this curse.
The gods tried using their divine power against this and partially succeeded in suppressing the curse. They secretly made heros and then let join infiltrate the demon kings ranks. Finally one fated day when Damian is poisoned continuously by the woman he loved for years, they made their move.
The once mighty demon king now had look of someone who fell ill, they used a poison that can even harm gods for this. These gods never learn do they. As thousands of heros blessed by gods and cursed by the demon king entered the battlefield, they're all killed by the demon king.
But as the rebellion is reaching it's end, a shocking thing happened, the demon king's lover shed her disguise and revealed herself as the Demi-God daughter of Goddess of Order. She stabbed the Demon King's heart and tried taking his source crystal that had the power and part of his soul. But as her arm stabbed the body of demon king she found no such thing.
Damian smirked and said," so the gods has fallen to the stage where they need to consumate with humans to produce someone like you. What a disgrace ", Laurentia asked," where is your source crystal? WHERE IS IT? ".
Damian laughed at her before his form started crumbling. He knew this day would come eventually, the day he realised, he was severely poisoned akd weakened he took the source crystal and did something astonishing combining it with the philosopher's stone and the staff of space-time god.
He made a device to reincarnate himself into the other world. But the world must have mana, this staff can detect such world and send him there. So Damian hid this mechanism and made it so, the moment he dies, this device will activate sending his soul into that world for reincarnation. And he only got one shot for this one. He thought he may not be able to complete it but he did.
Damian gave the Demi-God a middle finger before crumbling into dust. She indeed inflitrated too deep, even slept with him for this so called mission from her mother. He loved her and got betrayed, he isn't going to make the same mistake he did now. Whatever this world holds, he will build himself a fun life without any one dictating his choice.
The source crystal is like another heart for the demons. Since Damain became a demon king, he found this source crystal is extremely valuable to him. It contains 70% of his power and became a container for a part of his soul. This is also the most fatal weakness he got. He vowed to never form another source crystal like this.
Meanwhile in the divine realm. The gods slammed the tables. They made meticulous plans for this yet this proved to be nothing. Their faith is corroted now because of the damn demon king, they need his source crystal to remove the curse and make puppet to let that things suffer for eternity hunted again and again by heros. This may have also put a restraint on the demon race and allowed them to farm faith endlessly.
But now, this damn demon king once again defeated them. Their divine power is restricted from acting on the lower realm. Blatantly using that will not be good. In the end, they gathered all their resources to pay and descend to personally remove this curse not knowing another gift the demon king prepared for the gods.
As the Gods descended the believers knelt and started praying. The Gods did their usual speech of benevolent facade and removed the curse before leaving, but then something that made them furious happened. The curse took effect once again. Damian put a contingency against these gods.
He knew they will stop at nothing to gain faith, so he made a device to curse the faith of gods again and again if it gets dispelled and buried these devices in many places. The fall of demon king made other races who swore their loyalty to him furious.
The dragon race, the demons, elves, demi-humans who suffered injustice at the hands of humans banded together, united against the tyranny of humanity. Laurentia became weak due to the curse that Damian inflicted on her. Even though she removed it many times, the curse came back again and again.
After months of war, the alliance stood still and humanity also held on. So a ceasefire was signed because of the gods. Now their power decreased by huge margins because of the cursed faith they received. They need to purify and use it to retain their existence. Their power and authority also decreased as their faith also become less and less.