After learning of Qel-Droma's capture and pending treason trial on Coruscant, Kun intervened and immobilised the entire council that presided over Qel-Droma's case with Sith Magic, only his old master Baas was able to resist his spell. He offered Baas a place at his side. He refused and they fought. Kun proved too powerful and struck his old master down on the floor of the Old Republic Senate chamber. This murder opened the eyes of all around him who had not already seen his descent into the dark side.


Exar Kun in his last throesUnder him, the Sith were able to push the Jedi back as they were forced to abandon many of their strongholds. In his studies, Kun had discovered the secrets of the crystals aboard Sadow's flagship. Where Sadow had caused a binary star system to nova to cover his escape, Kun had the vision to use this extraordinary ability as an offensive weapon against Ossus, which was a few light-days from a cluster of red giant stars then known as the Cron Cluster. Kun would sweep down during the inevitable hasty evacuation and cherry-pick the best of the Jedi artifacts and tomes. The Sith Battleship was dispatched with Aleema aboard (with the connivance of Qel-Droma, who had been informed by Mandalore of Aleema's treachery). Aleema was not told that detonating five red giants ensured that they would supernova, and ensure her death in addition to that of the Jedi fleet defending Ossus which was to pursue her. The scheme worked almost exactly as planned.

During the stripping of Ossus, Ulic encountered his brother Cay Qel-Droma, who attacked him. Ulic defended himself all too well, killing his own brother. This murder broke the hold of the dark side and the Sith toxins, redeeming him. In horror, Nomi Sunrider stripped him of the Force. The fallen Jedi whom Kun took under his teachings recanted his foray into the dark side after being cut off from the Force. A broken man, Qel-Droma then led the Republic to Kun's temples on Yavin IV. On the jungle moon, Kun sensed he would not survive the Republic's coming attack. Thus, he drew upon the riskiest sections of Sith alchemy and drained the life-force of the entire Massassi race, binding his spirit to the temples they had built for him. He remained largely dormant and was even forgotten as the centuries passed.