The gray elves used their vast magics to create one of the greatest kingdoms on Alvena by creating the first kingdom of Alvena that wasn't truly on Alvena. With their powerful magics, they built an incredible latticework of cities that floated high above the planet's surface, like vast clouds of conjured steel and stone, held aloft by their supreme arcane power. Rivaled in power only by the mighty Gal'andri Kingdom on the surface, the gray elves lifted their entire race to the heights of the skies themselves. They called this kingdom Sk'liyl (or Sky Dance).
This ascension didn't come without a great degree of arrogance however. Quickly the strongest wizards in their society were becoming filled with delusions of their own power. As they now traversed the skies above the land, they felt as if they were gods themselves, and didn't need to heed the warnings that the old gods bid them when they passed on the secrets of arcane magic to them during the dragon wars centuries earlier. They dove deeper into the understanding of demonology and many of the arcane schools became obsessed with diabolism and their study of the hellish planes and the powers their masters possessed. They believed, foolishly, that they were powerful enough to be beyond the dangers of dealing with such powers. Belief and truth, however, are not always the same thing in the end.
It was in the city of El'tel Theli Nev'ar (the morning's star) that the first of the great corruptions emerged. The ruling wizard in the city were deceived by the promise of power and knowledge by the archfiend Si'se'lixa the Corruptor, the lover of the great demonlord Relkanos the Bloodlord. Si'se'lixa convinced the council of wizards to open a portal to their world so that she and her husband could bring their knowledge and blessings to the gray elves' world, and bring them to even greater heights of excellence. Little did the wizards realize the nature of their benefactors until the portal was opened. Instead of meeting risen beings of higher knowledge, they found powerful fiends that were interested in spreading their tyranny into this world, and using its resources to gain an advantage over their rivals in their homeworlds.
At first things seemed innocent enough. The fiends appeared in the guise of noble and beautiful humanoids of some unknown species, and spoke with gentle words and promises of wealth, power, and prosperity. They used their magics to improve life for the gray elves, and taught them to rely heavily on infernal powers in their lives. They dulled their senses with hedonism and subtle vices. The wizards, in their hunger for advancement, were easily lulled into a sense of security, and their students manipulated to slowly become reliant on their devilish masters. Everything was going according to the plans of the devil bride and her demon husband, and soon this world would be their own.
During an event known as the closing of the eyes, where all seven moons of Alvena were eclipsed, the evil pair struck. They used the portal that was opened by the gray elves to allow them to come and go to move in their own troops, and they began systematically slaughtering each wizard that could pose a threat to their invasion. Before the dawn of the eve and the opening of the eyes, the city of El'tel Theli Nev'ar was in flames and plummeting to the surface of the world as a battle raged upon its streets and towers. Six grand magicians were all that remained of the city's hope to stop the demon lord and his bride. Six, they knew, were too few to hold back the tide of the fiend lords. In a desperate gambit, the six used the last of their magics to attempt to overcome the fiends and their plans. A gamble that may have saved the world in the long run.
The magi uttered terrible incantations and unleashed the last of their ancient knowledge of the spells the gods had bestowed upon them. Along with their own city, they brought down countless more floating cities around them, which could have been used to open another hellgate.