Duel in the Dark Council Chambers (Kaggath)

When Darth Zash ordered her apprentice Kallig to kill Darth Skotia, Skotia's Master, Darth Thanaton, became suspicious of Zash and her deeds. Thanaton detested Zash and soon, he saw Zash and her apprentices as vermin that needed to be cleansed from the Sith Empire. After Zash supposedly died, Kallig took her place and began serving Thanaton. However, Thanaton sought out to kill every follower of Zash and as such, tried to get rid of Kallig. This act would prove to be his undoing. Kallig survived Thanaton's many assassination attempts and managed to build a power-base to fight Thanaton's forces. Seeing that all his attempts failed even after becoming a Dark Councilor, and after losing various apprentices, Thanaton called out a Kaggath on Corellia to defeat Kallig once and for all. When it became apparent that he would lose, Thanaton fled to Korriban to ask the Dark Council for help.

Darth Thanaton arrived on Korriban and went to the Dark Council Chambers to speak to his fellow Dark Councilors. Kallig arrived soon after and chased after Thanaton. After Kallig defeated Darth Enraj, who allied himself with Thanaton, Kallig entered the Chamber and confronted their nemesis. Thanaton said that Kallig and Zash were corrupt and needed to be rid of, but the Council pointed out that he had failed to do so personally. Kallig stated that Thanaton broke the rules of Kaggath, and as such is nothing better than his false words. The Dark Council stated that if Thanaton wanted to keep his reputation and honor, he had to defeat Kallig in a duel. Thanaton continued to speak of the value of tradition, which angered Darth Ravage, who turned to his fellow Dark Councilor, Darth Mortis, and stated that if neither Kallig nor Mortis could do anything, he would kill Thanaton personally. Enraged, Thanaton declared he would not be betrayed by the Dark Council, would kill the Sith Lord, and would later hold the Council accountable for their impotence.

Kallig and Thanaton fought against each other, but Thanaton found himself outmaneuvered and losing. Refusing to accept defeat, Thanaton unleashed bolts of Force lightning, but Kallig effortlessly deflected his attacks with but a flick of the wrist. The now desperate Sith Lord used his full powers to kill Kallig, calling Force storms upon his enemy and shooting Force lightning. While he was able to briefly restrain Kallig, they, thanks to the ghosts bound through the Force walk, was able to survive his attack and dispel it. Thanaton attempted to conjure another Force storm, but Kallig then utilized a powerful Force push that pinned Thanaton against the opposing wall, before releasing him. As his rival looked on with crossed arms, Thanaton drew his lightsaber and charged, only to to be stopped mid-strike and forced to his knees by his opponent. Thanaton, disguising his efforts by bowing his head, attempted to release a counterattack, but Kallig saw through the ruse and attacked him with Force lightning. Thanaton, heavily injured, crawled to his fellow Dark Councilors. The Dark Council saw that Thanaton was weaker than Kallig and thus had lost the Kaggath. Darth Mortis apologized to Thanaton, before snapping his neck with the Force.

As Kallig proved to be the more powerful Sith, the Dark Council granted Kallig Thanaton's seat on the Dark Council. Darth Ravage voiced opposition to putting just a Sith Lord on the Council, as usually Darths attain the seat. Darth Marr ordered him to be silent, stating that Kallig had earned the position. He then remedied Ravage's protest by granting Kallig the title of Darth Nox. With this act, Nox became the master of all the Sith and members of the Sphere of Ancient Knowledge, only answerable, along with the rest of the Dark Council, to the Sith Emperor himself. Mortis then adjourned the meeting, advising Nox to return to Dromund Kaas to ensure the fealty of the Sphere of Ancient Knowledge and promised to inform Nox the next time the Dark Council would congregate.

• Star Wars: The Old Republic Encyclopedia