Duel on Lehon In 1000 BBY , a lightsaber duel was fought on the planet Lehon between two Dark Lords of the Sith : the Twi ' lek Blademaster Kas ' im and his former apprentice , Darth Bane . Kas ' im followed Bane to Lehon and found him in the Rakata n Temple of the Ancients , where he presented the Human with the choice of either rejoining the Brotherhood of Darkness to which Bane had once belonged , or making Lehon his final resting place . When Bane refused , an intense lightsaber duel ensued . Bane , who was considerably stronger in the Force , maintained the offensive in the beginning of the duel . The tide turned when Kas ' im split his double - bladed lightsaber into two separate weapons and attacked his opponent with a previously unrealized degree of ferocity . Bane was forced onto the defensive , and was just barely able to maneuver his way out of the temple before Kas ' im blasted him with a wave of Force energy . Bane reciprocated the attack , and Kas ' im absorbed its brunt by shielding himself with the Force . The temple entrance in which Kas ' im stood , however , was obliterated by Bane ' s exertion , and the Twi ' lek was unable to avoid being crushed to death under the tons of rubble that fell upon him . Prelude . In 1000 BBY , recently promoted Dark Lord of the Sith Darth Bane abandoned the Brotherhood of Darkness in the midst of a war with the Jedi Order and the Galactic Republic . Convinced that the Brotherhood was nothing more than a flawed collection of individuals whose affirmation of the Force ' s dark side had diluted its potency , Bane left them to embark on his own search for Sith enlightenment . His quest led him to Lehon , or the " Unknown World , " the planet where the Jedi Civil War of nearly three thousand years prior had ended . Once there , he located an ancient Rakata n temple , wherein he discovered and began tedious exploration into the Sith holocron of Darth Revan . Meanwhile , the rest of the Brotherhood of Darkness had gathered on the planet Ruusan to engage in a final campaign against the Jedi ' s Army of Light . Githany , Bane ' s former mentor , experienced a Force premonition that involved Bane coming to Ruusan to destroy the entire Brotherhood . She informed the leader of the Sith , Kaan , of this , and together they conspired to bring Bane back into the fold , lest the events of her vision become reality . Githany knew through her Force bond with Bane that he had gone to Lehon ; to this end , Kaan enlisted the Twi ' lek Blademaster Kas ' im to find Bane and speak with his former apprentice on Kaan ' s behalf . Kaan ' s instructions were clear ; if Bane could not be swayed , then Kas ' im was to kill him . The Twi ' lek departed in a Sith Buzzard starfighter and made his way to the Unknown World . The duel . Part one . Kas ' im homed in on the beacon from Darth Bane ' s stolen starship , " Valcyn " , and landed his starfighter nearby . He also sensed Bane ' s presence , which he followed to the Temple of the Ancients , battling and killing a rancor in the process . Kas ' im found Darth Bane in the Temple ' s innermost chamber when he arrived , startling the man and causing him to activate his lightsaber . The two of them entered into a debate over the Brotherhood ' s ability to actually destroy the Jedi , and the Twi ' lek ignited his double - bladed lightsaber as he attempted to convince Bane to partake in the war effort on Ruusan . Bane refused to be discouraged , and when he declined Kas ' im ' s final offer to either rejoin the Brotherhood or die on Lehon , the Blademaster leaped in to engage Bane in lightsaber combat . Darth Bane realized immediately from their initial exchange of blows that his former teacher had withheld his true ability from him during their training sessions . He was still able to just barely defend himself , which surprised Kas ' im , who had advanced with the intention of bringing a quick end to the contest . The two men openly took notice of how the other ' s skills had improved since their last duel , and both reevaluated their tactics before resuming the battle . Kas ' im engaged in a relentless offensive , but Bane surrendered completely to the dark side and with his lightsaber erected an impregnable defense . He then became the aggressor , driving Kas ' im back and forcing him to retreat from the chamber . Bane leaped forward after him , and missed by less than a centimeter a blow that would have crippled his opponent . Kas ' im switched several times between different strategies and dueling styles , but Bane anticipated each change and pressed his advantage . He had seen and developed counters for every technique the Twi ' lek could implement with his saberstaff ; that — combined with his superior knowledge of the Temple ' s interior layout — saw the duel rapidly progressing in Bane ' s favor . Kas ' im , who had become desperate in the face of impending defeat , performed a series of acrobatic maneuvers as he attempted to escape Bane ' s assault . When he realized that his opponent was forcing him into a dead - end hallway , Kas ' im used the Force to blast open the door of an adjacent room , into which he dived . Noticing that the Twi ' lek had effectively trapped himself , Bane stood in the doorway and relished in his apparent victory . Kas ' im , exhausted though he was , admonished Darth Bane for not taking the opportunity to finish him . The Blademaster then twisted the hilt of his double - bladed weapon , which separated into two individual lightsabers , and attacked his adversary . Duel ' s end . Bane was completely unfamiliar with Kas ' im ' s two single - saber variant of Ataru and was almost instantly outmatched . Despite his superior Force ability , what had once seemed like a certain victory for Bane turned into a fight for his life . Kas ' im struck from all angles in his relentless onslaught , forcing Bane to concede more and more ground in a battle he believed he could no longer win . His only recourse was to work his way toward the Temple ' s only entrance in an effort to escape . Kas ' im realized Bane ' s intent when the opening came into view , but he was momentarily unbalanced by a Force push from Bane as he back - flipped through the entrance onto the landing outside . Bane ' s flip had carried him too far , however , and he landed shakily on the edge of the landing ' s declining staircase . Kas ' im followed with a telekinetic blast that knocked Bane down the stairs , but by shielding himself with the Force , Bane was able to avoid sustaining serious injury . Kas ' im stood under the Temple ' s archway and stared down at Darth Bane as he recovered . He told Bane that attempting to flee was futile , because Kas ' im planned to pursue him wherever he went until which time the Twi ' lek was able to kill him . He suggested that Bane end the duel then instead of prolonging the inevitable , and Bane , who had been gathering Force energy while Kas ' im spoke , agreed as he unleashed it in a devastating Force wave against his foe . Kas ' im shielded himself with the Force at the last moment , but he had not accounted for the destructive impact Bane ' s attack would have on the Temple ' s structure . The sheer power of the energies Bane released annihilated the Temple entrance , which collapsed and fell , crushing Kas ' im below . Indifferent to the death of his former mentor , Bane left the Twi ' lek under the rubble and set out for Ruusan . Aftermath . News of Kas ' im ' s death preceded Darth Bane ' s own arrival on Ruusan and reached Lord Kaan via a message drone dispatched by Bane himself . Also included in the message were the details for creating the thought bomb , an ancient Sith weapon that unleashed the pure destructive energy of the dark side . Disguised as a peace offering , Bane hoped that Kaan would detonate the thought bomb and in doing so obliterate every Force - sensitive being on Ruusan . When he finally arrived , Bane was able to convince Kaan to use the thought bomb , which he employed during the final battle for dominion over Ruusan . As Bane had anticipated , the thought bomb wiped out Kaan and the entire Brotherhood of Darkness , as well as most of the planet - side Jedi ; Bane had indeed destroyed the Brotherhood just as Githany had foreseen . The elimination of his rivals paved the way for Darth Bane to create a new Sith Order of his own design — one that , instead of dispersing the strength of the dark side throughout numerous Dark Lords , focused the power of the Force in two individuals : one Sith Master to embody that power , and a single Sith apprentice to crave it . Behind the scenes . The duel on Lehon appeared in the first novel of author Drew Karpyshyn ' s " Darth Bane " trilogy , titled " " . The event was later alluded to in " The Complete Star Wars Encyclopedia " , wherein Kas ' im ' s entry notes his death at the hands of Darth Bane .