Entropy is the general trend of the universe towards death and disorder.
In this universe, danger exists in every furthest reach. As millennia passed, this danger did not sit idle - it crept, ever closing in around the bounds of the universe. Like an insect caught in a hand, entropy slowly closed its grip around all that was good and peaceful. Civilization did not go effortlessly - entire worlds fought, or ran, or hid. But entropy is a law of nature. Slowly but surely, order was ground to dust.
This world tells the story of that resistance. The fight against the inevitable. An attempt to carve out a bit of order, a bit of life from this slow march of death.
Tariel was once a world populated by species that have long been forgotten. Nobody knows what became of the First Men - but their ruins are still occasionally discovered in great caverns of the Underhalls or Underneaths, deep in forgotten forests, inaccessible mountains, or beneath seas that ages ago may have been deserts. Whatever befell upon them disrupted reality itself in some way, it seems, as many believe these ruins can reappear out of nowhere, in places sworn to have been explored in the past.
But what is important, is that Tariel was no longer populated by sentients when the Empyreals arrived. Nobody knows where the Empyreals first came from. Scholars from the Order of the Circle believe they were originally beings from Aetherius who somehow tied themselves to the Mortal Realms permanently, allowing them to exist as multi-dimensional beings. Others believe they are beings that transcend reality the laws of nature and magic entirely. What is known is that they wielded immense power - and they were afraid. Their fear was justified. The bones of the Empyreals are now the sites of the Godsgraves, places mortals avoid for fear of curses.
Worse yet, corruption seeps into Tariel, weaving its way through The Veil, infecting spell casters, growing in the dark forgotten corners of the world.
How much longer can the world hold out? The end is near, but it's not here yet. This story here is not about the end, it's about carving out a bit of life before its gone. One of the final, listful sighs before age takes its toll and decay sets in.
Dungeons & Dragons 5e