Shadow
This ingenious arcanist was the first to theorize of demiplanes. A student in Karsus’s academy for magical study, Shadow published a highly criticized work on the planes. The concept of demiplanes was in opposition to the common thinking that all planes originated from Netheril like branches upon a tree. His work earned him the enmity of the establishment, and he was sent into exile at the Fortress of Burmstone in the far north. His research was banned and assassins were sent to claim his life for his theories. All study of demiplanes and quasiplanes was banned in several cities. In Karsus, though, Shadow was asked to stay and continue his studies; Karsus felt Shadow was onto something important. Shadow invited other “underground” researchers to help him in his investigation, and Karsus financed the whole operation. With the backing of Karsus he published conclusive proof of the existence of the demiplanes. The first plane discovered was named after the arcanist, and dozens of other arcanists entered the demiplane to discover its properties. Many never returned, but those who did exclaimed that the plane was appropriately named: the Demiplane of Shadow. Eleven years later, with permission from Karsus himself, Shadow published another work, this time on the Demiplane of Shadow, entitled Shadows: The Palpable Cohesion of Formless Corporeality.
In 3469, Shadow became involved with a beautiful bard from Ioulaum, Alashar Crywinds. As the two planned to get married, however, Alashar revealed that she was actually an assassin sent to slay the arcanist for his work on demiplanes. She reveled this after poisoning Shadow who she had come to love, and quickly poisoned herself immediately following. Shadow has made preparations for lichdom in death, and was responsible for the experiments that created Coldlight Walkers. The first Coldlight Walkers were created out of villagers from Scourge, the hometown of Owyn of Netheril. Eventually, Shadow abandoned the Fortress of Burmstone in favor of the legendary Tower of Qar'zad where he felt he would better perform his evil magic in service of Karsus
Using Shadow’s research, Karsus had a special arena that contained level-draining undead. For particularly dangerous criminals, Karsus turned them over to the city of Yeoman’s Loft, where they were used to power life jamming vessels (ships whose power sources were the life-energy of their victims).