Teraptus

Teraptus the Destroyer. Or, as he is more known, The World Dragon. He brought death and destruction to the world, destroying hearth and home everywhere he went. He slaughtered, he deceived, he enslaved. His tyranny knew no bounds. His influence spread wide, his legend grew, his power continued to swell.
For nearly a millenia, the races of the world served him. Unable to break the yokes of his tyranny, they were forced to sacrifice and toil in labors, constructing temples and statues and edifices in his image in all corners. Until slowly, the peoples of the world began to revolt. Small rebellions and refusals to comply with his commands, and the commands of his cultist followers.
It began in earnest in Therengia, where a group of hunters slaughtered the cultists enforcing his rule, and began rallying their countrymen to their cause.
Soon the motley lot became a full fledged army of revolutionaries, hungry for freedom from his oppression. Men, Elves, Dwarves, Tabaxi, even Gnomes and Orcs all stood shoulder to shoulder in an attempt to overthrow his tyrannical rule.
During the battle, several warriors stood out among the rest, breaking free of the army and sneaking deep into Teraptus' lair, where they confronted the World Dragon without the aid of his armies. There, using powerful magics and strength of arms, they struck a blow which nearly killed him.
Weakened and badly wounded, Teraptus attempted to flee and recover his strength. But the emboldened people had made a desperate gamble, one that changed the course of Kermoria forever.
One of their warriors, a young Elven woman named Periel, had been horribly wounded during the fighting. Knowing she could not pursue the Tyrant, she reached into her soul, tapping into her own life force to bind him eternally.
As the legend states, Periel bound the Tyrant to an eternal slumber in a temple deep underground, so far beneath the earth as to be the core of the world. There, she sings softly, night and day, to ease his mind and keep him confounded and unable to act. And there she shall stay, her voice often heard in the echoes of sea-shells held to the ear; the soft song of a lonely woman, bound forever to a duty greater than herself.
Those heroes, and their actions, freed the world from the grip of the World Dragon. Their actions brought about true divinity to the world, and they became The Thirteen, the Gods and Goddesses now known to all the races, granting their power to their followers.