Firble Gemcutter

Firble Gemcutter was one of the adventurers known as the Planeswalkers. A cunning assassin and skilled wizard, he was posessed by a shard of the Shade Lord Telamont Tanthul before defeating the ancient Netherese wizard in the shadowfell. Firble collected the soul gems of the six fallen Princes of Shade and studied them for a time. His fellow adventurers grew suspicious of him, and he eventually disappeared without a word after leading an army of shades against the modron march in Waterdeep.
Firble would return to the shadowfell and claim the title of Shade Lord in Gloomwrought, enslaving the shades he had previously led into battle and using the soul gems to transform into a shade lord (transcending his mortal form). This, however, attracted the attention of the Raven Queen and he became one of her thralls. He continued his quest to absorb the remaining shade princes, first encountering Melegaunt in the shadowfell. He failed to completely drain him, and instead forced Melegaunt to retreat to the material plane where he became trapped within a falchion in his ancestral tomb (where he was discovered by a bedine nomad named Zarud, whom he enthralled).
About 30 years ago, the nomadic bedine began noticing activity from the ruins of the city of shade. Strange shadowy creatures began attacking travelers on the black road. Purple worms began to migrate away from the region. One day, locals awoke to a massive floating city in the skies. Built atop an upside-down mountaintop, the city seemed to be made of black stone that absorbed all light. Shadowy winged creatures began pouring from it, and hounds of darkness roamed the land beneath it. For a week, the floating city traveled across the desert. Wherever it roamed, shadowy creatures patrolled the land beneath it. Then, as quickly as it had arrived, it disappeared again. Firble had risen the city of Gloomwrought as the new Shade Enclave and ventured out into the desert, enthralling warlocks to his service.
Firble would later send one of his warlocks to Silverymoon to research the Phaerimm and the sharn wall in his plan to draw out the remaining shade princes. When he sensed the arrival of Melegaunt and the Savage Seven in the underdark, he sent Nalzmyr's undead father to stop them and capture Melegaunt.
After the Savage Seven perished, Firble absorbed the remaining princes of shade (except Melegaunt, who remained as the sword "souleater") while they gathered in the city of Chaulssin. This was enough to elevate him to the level of power of the previous Lord of Shade Telamont Tanthul. He lifted the city of Gloomwrought from the ground and gathered an army of shades and shadar-kai to him, then traveled to the material plane where he attacked the city of Sundabar. His army was defeated by the alliance of the Silver Marches, and he was defeated by Teldaron Silvermask and a group of adventurers. The city crashed atop Sundabar, destroying it entirely.
Following his failure, he was imprisoned by the raven queen in the shadowfell and eventually discovered by the hellraisers. Nalzmyr, Melegaunt's champion, struck him down and freed the shade princes.