Darth Tenebrous ' s Sith Master A Twi ' lek Dark Lord of the Sith reigned as the Sith Master of the Bith male Darth Tenebrous during the final centuries of the Galactic Republic . The duo followed the lineage of the Sith Lord Darth Bane , adhering to his Rule of Two , which restricted the Sith to one Master and one apprentice . During the Master ' s reign , the Twi ' lek opened a hole in the Force , allowing the Jedi Order to feel the dark side for the first time in over eight centuries after the final battle of the New Sith Wars . Eventually , the Twi ' lek was slain by Tenebrous , who carried the Sith imperative forward by taking the Muun Hego Damask as his apprentice , dubbing him Darth Plagueis . Biography . In the final centuries of the Galactic Republic , a Twi ' lek who was sensitive to the Force joined the Order of the Sith Lords , eventually ascending to the rank of Dark Lord of the Sith . In keeping with the Sith Lord Darth Bane ' s Rule of Two , which limited the Sith to a Master and apprentice , the Twi ' lek Sith Lord eventually took the Bith male Rugess Nome as his pupil , naming him Darth Tenebrous . The Twi ' lek Sith Master and Tenebrous were dedicated to advancing the Grand Plan , which was a Sith imperative focused on destroying the Jedi Order and the Republic . The pair worked for years to develop a virus that would target and sever a Jedi ' s connection to the Force . However , the Master and Tenebrous ultimately abandoned the project . At some point during the Sith Master ' s reign , the Twi ' lek opened a rift in the Force , allowing the Jedi Order to sense the dark side of the Force for the first time in the eight centuries since the final battle of the New Sith Wars . Darth Tenebrous ' s Sith Master burdened the Bith with studying the Force , which Tenebrous viewed as simple . The Bith eventually came to believe that the Force was an energy source that he could manipulate in order to achieve his goals . After reading the prophecies in the Journal of the Whills regarding the Chosen One who would bring balance to the Force , Tenebrous was determined to use a variation of the essence transfer — a Force technique that enabled its user to transfer his or her consciousness into another body — at the moment of the individual ' s birth , thus making himself the Chosen One . Around 167 BBY , when Tenebrous ' s calculations for his scheme were complete , the Twi ' lek was slain by his apprentice , who went on to take the Muun Hego Damask as his apprentice , naming him Darth Plagueis . Plagueis , the Sith Master ' s eventual successor , acknowledged the Twi ' lek ' s role in advancing the Grand Plan to topple the Jedi and the Republic and opening a rift in the Force . The Muun Sith Lord recounted the Master ' s and Tenebrous ' s achievements to his apprentice , Darth Sidious . Personality and traits . The Twi ' lek Sith Master was dedicated to the Sith initiative to topple the Jedi and the Republic . Despite the Master ' s and Tenebrous ' s attempts to create a virus that would separate the Jedi from the Force , they ultimately abandoned their efforts . Tenebrous viewed his Master as simplistic and tottering . Powers and abilities . Tenebrous ' s Master was capable enough to cause a rift in the Force that enabled the Jedi Order to feel the dark side ' s presence for the first time since the New Sith War ' s final battle . However , the Twi ' lek was not able to withstand Tenebrous , who slew his Master . Behind the scenes . Darth Tenebrous ' s Sith Master was first mentioned in the short story " The Tenebrous Way " , which was written by Matthew Stover for " Star Wars Insider 130 " and released in December 2011 . The Sith Master was later mentioned in the novel " Darth Plagueis " , which was written by James Luceno and published on January 10 , 2012 . Tenebrous ' s Master ' s species was established as a Twi ' lek in the novel .