Quintus Karesh

Quintus Karesh was a powerful archwizard, though not one known for his kindness. Karesh was a man who craved power and sought it through magic, spending years to become a master at crafting spell gems. He was convinced if he could make the ultimate spell gem that the power of such an artifact would make his magic unrivaled. Karesh tried for years but all the gems he could find would shatter during his experiments, unable to contain the immense magical energy such an artifact would require. He had nearly given up when he heard of a set of perfect gems given to a dwarven king by their god Dumathoin, Dwarven God of Mining.
Karesh presented himself to the dwarven king as a friend, bringing gifts to honor the good king and claiming he sought to become one of the king's advisor. Recently blessed with much good fortune, the king believed Karesh's lies and was taken by surprise when he was woken with the news that Karesh was gone and so were the gems of Dumathoin.
Karesh used the god-touched gems to create the Quintus Gems, a full set of artifacts that could grant ultimate power to those who wielded them all. But Karesh's actions had not gone unnoticed by Dumathoin and the dwarven deity was not amused. He placed his magic upon the gems, giving each a degree of will that allowed them to choose wielders. Wielders that fit the standards of Dumathoin himself, which Karesh certainly did not after his insult to the god and dwarven people.
While Karesh was able to draw a trickle of power from the gems, it was all he could ever manage without being one of their chosen. He became obsessed, spending the rest of his days trying to figure out somehow, someway to bend the gems to his will. He never succeeded and died alone in his tower, a miserable and forgotten man who was a far cry from the great wizard known throughout the lands that he'd always wanted himself to be. His estate was liquidated and the Quintus Gems were scattered, often finding themselves in the hands of chosen heroes when they sensed they were needed.
Years later, the spirit of Karesh remained in his tower and sensed several Quintus Gems nearby. Karesh's tower was in a bubble of air magically projected at the bottom of a lake. His magic pulled at the gems like a magnet, drawing the Barrel Boys through the water as their lakeboat passed overhead. The group fought their way up the tower, past ageless pets and minions Karesh had collected during his travels throughout the realms. At the top of the tower they found the undead Karesh. Though severely weakened, Karesh was still a powerful foe who attacked the adventurers in an attempt to reclaim the gems they carried. But his power had waned too greatly and he was defeated, forcibly sending the wizard to the afterlife and ending his interference on Nexus' history.