Ioulaum

Ioulaum was a great archwizard of Netheril, a beloved champion of his people and the inventor of both the mythallar and the flying enclaves of his empire. When Ioulaum abandoned Netheril to escape the “life drain” dweomers of the phaerimm in -339 DR, panic spread at the news of his disappearance, leading to Karsus casting his spell “Karsus’s Avatar.” Since the fall of Netheril, Ioulaum has survived as an elder brain (the central brain of an illithid community) lich.

Activities
Under the guise of the Oracle of Ellyn'taal, Ioulaum extracted a terrible price for the information he provided - the voluntary, permanent loss of some portion of the questioner's sanity or the knowledge of a powerful spell that Ioulaum did not yet know.

Early life and The Excursion Into Extinction
Born in Seventon in -3315 DR, Ioulaum soon rose to prominence when in -3145 DR he led a major battle known as the "Excursion into Extinction", bringing thousands of Netherese spellcasters and warriors to mount an attack against the largest concentration of orcs in Netheril's land at the time.

The Mythallar Era
Ioulaum was most famous for his invention of the mythallar  in -3014 DR. The mythallar dug deep into the raw, unfiltered magic of the weave. The arcanists of Netheril used it to create quasi-magical items - items that were permanent as long as they were within the one mile range of a mythallar.

With the establishment of the mythallar, Ioulaum created the first mythallar-powered item in -3011 DR and the first floating city in -2954 DR.

The Rise and Fall of Netheril
Between -2758 DR and -2208 DR, Ioulaum trained thousands of arcanists to become archwizard's in their own right. He also managed to greatly augment and strengthen his mythallar using precious metals. At the height of the empire's growth between 2207 DR and -1206, Ioulaum frequently journeyed across Netheril helping to establish new floating enclaves or investigating strange magic. However from -696 DR the stability of Netheril became steadily undermined by both the Phaerimm and numerous disasters. This caused Ioulaum to become increasingly reclusive as he attempted to research ways of countering the threat of the Phaerimm, to the extent that he handed the day-to-day running of Xinlenal to a number of archwizards.

As the Oracle of Ellyn'taal
Since the waning years of Netheril, Ioulaum survived as a Lich after undergoing the transformation in -371 DR and created a lair in the Northdark.

By -339 DR, Ioulaum fully retreated to his Northdark lair and began training an ever-growing number of apprentices fleeing the decline and eventual fall of Netheril. It was believed that during this period that Ioulaum was responsible for the creation of the first alhoon from his illithid students.

In 329 DR, Ioulaum was apparently slain by a cabal of illithiliches. Ioulaum's last human apprentice, Tabra, witnessed what she believed to be her master's battle with his own students. This was actually a rite concocted by Ioulaum in an attempt to create an undead elder brain that he would then merge his own sentience upon.

In revenge for her master's apparent death, Tabra slaughtered the last few of Ellyn'taal's mind flayers by casting "Ioulaum's Longevity" on herself in the midst of the community. She then destroyed all records of the spell (except her own and those that Ioulaum himself had secretly hidden away) and fled to the surface.

By 1372 DR, Ioulaum survived in the form of an undead elder brain, known as the Oracle of Ellyn'taal. Only Ioulaum's undead servitors and the ghosts of the mind flayers slain by Tabra remained with him. The few brave explorers who had stumbled upon the Oracle of Ellyn'taal had gained bits of arcane knowledge dating back to the height of Netheril from their meetings with it.