A male humanoid, Baddon Fass was a Dark Side Adept in service of the Galactic Emperor Palpatine. Fass was enamored with the Dark Side and felt that his mastery of it made traditional weapons unnecessary since at a gesture or thought he could choke the life out of someone, compel the weak minded or inflict pain on non Force users. He was mirrored in this in many ways by his partner, Zasm Kath, who also eschewed weapons in favor of relying upon the Force, though this was due more to a lack of training or proficiency with physical weapons as they both felt that their powers were the far easier method. Fass delved into sorcery and alchemy, but was limited by his own aptitude levels. At some point, Fass was promoted into the Dark Side Elite, a selected cadre of Dark Jedi imbued with Force power and will directly from the Reborn Emperor. When the Emperor was slain a second time in 10 ABY, the leader of the Dark Side Elite, Executor Sedriss QL assumed command of the Imperial forces, launching Operation Shadow Hand.
As part of that operation, Fass and fellow Darkside Elite member, Zasm Katth were dispatched to the moon Nar Shaddaa with the Star Destroyer Invincible to recruit Boba Fett for his Underworld contacts, capture the Millennium Falcon to bring Leia Organa Solo back to Byss, and finally to eliminate the Jedi woman Vima-Da-Boda.
While commanding the Invincible in orbit, Fass and Katth witnessed the Falcon arriving on the moon. They attempted to lock onto it with a tractor beam, but the vessel slipped away and took hiding in the mazelike canyons of structures. The darksiders ordered the Invincible to maintain its blockade in orbit while they descended to the surface with a platoon of Darktroopers and proceeded with the plan of recruiting Fett. The two confronted the bounty hunter, demanding him to provide his services for free. The bounty hunter refused, drawing his blaster on the pair of Dark Jedi, stating that he and Vader had once had an understanding that he only worked for pay. Fass retorted that Vader's authority had passed to the Darkside Elite and proceeded to strangle Fett with a Force choke. While Fett was struggling to breathe, Fass mockingly threatened to reveal secret information about him to the wider galaxy and reduce him to a slave. When Fass ordered the Darktroopers to remove Fett's helmet, the bounty hunter blasted them away with wrist-mounted rockets, almost killing Fass, who could not block the attack without a weapon, forcing the sorcerer to dodge out of the way at the last moment. Fett used the distraction to retreat aboard his ship, the Slave I and escape. Furious at being defied and evaded, Fass planned to make Fett pay. However, Dark trooper team two reported that they had spotted the Falcon parked inside the workshop of mechanic Shug Ninx forcing Fass to prioritize obtaining Solo above revenge on Fett.
Fass and Katth proceeded toward the reported location, but their Force sense notified them about the presence of the Jedi Vima-Da-Boda nearby. Remembering their orders to take out the woman, Fass ordered the dark trooper Grath to open fire on innocent bystanders with a turbocannon in hopes of killing the Jedi hiding among them. The elderly Jedi, however, managed to evade capture and was rescued by the Solos, who had also taken out dark trooper team two in the hangar. Arriving inside the hangar, Fass and Katth contemptuously looked upon the bodies of their fallen troops and left a detachment of stormtroopers aboard the ship, before returning to the Invincible to head off any potential escape if Solo had abandoned the Falcon. However, the Solos returned to the Falcon with Vima-Da-Boda and took out the stormtroopers, taking the ship to escape from the moon. They were detected by Mako Spince, the overseer of the Traffic Control Spire and an old rival of Solo's. Spince promptly informed Fass and Katth about the Falcon's trajectory.
Hoping to capture the ship, Katth ordered the Star Destroyer's tractor beam to full power, although Fass advised his companion against doing so. Thinking creatively, Solo maneuvered the Falcon under the Traffic Control Spire, which was caught in the tractor beam instead, and due to all the power being shunted into the beam, the entire spite was ripped from the ground instantly and hurtled toward the Invincible. Realizing the danger, Katth the tractor beam disabled and Fass moved to comply, but it was too late. The spire pierced the Star Destroyer's hangar bay and erupted through the upper hull, badly damaging the engineering section, disabling its thrusters and making the ship fall into the surface of the planet, destroying the Invincible and killing both Fass and Katth along with the entire crew. Palpatine meanwhile was reborn in another clone body, and the news of the death of two of his Elite was met with great irritation by the Emperor, and soon, Palpatine raised replacements for the pair from the ranks of the Darkside Adepts.
