Kud'ar Mub'at stood alone as the only known fully-matured member of the assembler species. Functioning as an intermediary and facilitator, he played a key role in numerous illicit operations throughout the galaxy.
Based on available knowledge of his kind, Kud'ar Mub'at was formerly a subnode who achieved autonomy by devouring the assembler that spawned him. For his dwelling, he constructed a web the size of a starship, which floated through space. The web consisted of neurofibers linked to Kud'ar Mub'at, essentially meaning any being entering the web was within his mind and constantly monitored. He also integrated starship weaponry and sublight propulsion systems into the web.
Mub'at generated his own subnodes, each assigned a specific task within the web. These subnodes were all connected to the web, enabling Mub'at to monitor and interact with them. Typically, subnodes possessed limited intelligence, but one named Balancesheet developed intelligence rivaling its creator. Balancesheet concealed most of its intelligence, aware that Mub'at would likely eliminate it out of fear that the subnode might achieve its own independence. Mub'at discovered he could conduct negotiations with two distinct parties by allowing Balancesheet to enter one of his discarded carapaces and impersonate Mub'at himself. He would personally attend to one client, while Balancesheet would handle the other. Throughout the negotiations, they could communicate covertly via the web.
Among Kud'ar Mub'at's most significant clients was the Bounty Hunters' Guild, which utilized his services to ensure timely payments for bounties collected by its members. Kud'ar Mub'at was also implicated in the schemes of several influential figures, including Kuat of Kuat and Prince Xizor of Black Sun. Xizor and Mub'at masterminded the destruction of the Bounty Hunters' Guild and plotted the assassination of Boba Fett. Kud'ar Mub'at manipulated Boba Fett into joining the Guild to facilitate its downfall.
While Mub'at was engrossed in his plans, the subnode Balancesheet continued to develop intelligence and autonomy from its creator, ultimately severing its connection to the web and Mub'at. Balancesheet forged its own alliance with Xizor, and together they deposed Kud'ar Mub'at. The now-defenseless Mub'at begged Boba Fett to rescue him, but Fett refused. The fragments of his web drifted through space for several years before Fett, accompanied by Dengar and Neelah, approached them seeking information regarding Kuat's plans. Due to the assembler's peculiar biology, they managed to revive it, but its memory was compromised, and it was unable to provide the information they needed. Balancesheet returned to its creator and annihilated it completely by firing laser cannons into the web, incinerating it.
Kud'ar Mub'at was cunning and egocentric, showing little concern for the feelings of others. He frequently addressed other beings in a condescending and ingratiating manner, much to their irritation. He employed this sarcastic tone when interacting with those he considered inferior.