Think of: Warcraft; Dark/Demon’s Souls; Final Fantasy 14; Bloodborne; Castlevania; mythology of Northwestern Europe & Kabbalistic cosmology
Legends abound of the mysterious lands to the north. Few from outside have traversed the fog-shrouded mountains barricading the northern lands, and fewer still leave with stories to tell. These weave a vision of a land out of time, a land that manifests one's dreams with a power impossible to truly grasp, a land ruled by ancient dragons and dense with arcane forests. It is called many names by those of other regions, but to the elves who originate there, it is Tron Daurat, the Golden Throne.
Since the dawn of time, Tron Daurat has been a land of primordial energies separate from the rest of the world. The immortal elves built their kingdom alongside the dragons and ruled their isolated haven, content to study the primeval magic of the world around them and live in blissful tranquility. Rarely did they look past the mountain bulwark protecting them to the rest of the evolving world; mortal conflicts were slow to develop and fleeting compared to the elves' eternal lives. Mortals thought Tron Daurat to be the land of the ancestral gods, and the elves soon viewed themselves as those same deities.
That was until, for reasons still unknown, their own leader, Emperor Malkuth, looked beyond the light of the sun and called to what he saw there. Stars fell from the sky, and around their craters day turned into eternal night. The dark energies of the fallen stars tainted the magic around them to create demons: living horrors spawned from fear, cruelty, and unwanted thought. Madness consumed the primordial dragons, twisted natural life into more abominations, and even tainted the elves into blood-hungry monstrosities. Worst of all, this darkness consumed the Emperor and the citadel of the elves, fragmenting their civilization into whatever sun-blessed pockets of dukedom still remained. This cataclysm and the demons that manifested from it would thenceforth be collectively named the Nightmare.
Now the once-proud elves are steeped in conflict against the Nightmare, struggling to stay united and build their strength against the demonic horde before it overwhelms their home and floods the world. All the while, their former emperor plots in his mountaintop citadel of Pandaemonium, commanding horrors to unknown ends beneath an endless night.