During an attack on the planet Mardona III as part of Operation Ringbreaker, Namir wanted to take over a housing block, leading Mzun to express concern for the safety of the occupants. Later on, during another attack on Nakadia, the alien took part in destroying a bioweapons warehouse. When the company was stranded on the planet Sullust awaiting an Imperial counterattack, Mzun tried to act like the company was going to win the upcoming battle. Twilight Company ultimately won against the Imperial assault.
Mzun served in the Rebellion against the Galactic Empire as a part of one of its companies, the 61st Mobile Infantry, better known as Twilight Company. Following the death of Sergeant Fektrin during a raid on an Imperial heavy freighter in 3 ABY, Mzun stepped in to take charge of the late sergeant's squad. Following the loss of Twilight Company's captain, Micha Evon, at the Battle of Hoth that same year, and the other Twilight officers during an infiltration of their CR90 corvette, the Thunderstrike, on the same day, Twilight Company hid on the pirate backwater planet Ankhural to repair the corvette and its escort, the Braha'tok-class gunship Apailana's Promise. Mzun participated in the meetings held between the most senior of the company.
After First Sergeant Hazram Namir was informed that a number of soldiers were considering deserting, including recruits from the Mid Rim planet Haidoral Prime and some of Fektrin's old squad, he consulted the matter with Mzun and the other senior Twilight members in one of their meetings. Mzun let out a series of babblings in a different language, which resembled outrage to Namir. The first sergeant ultimately decided to solve the deserter problem by splitting the reported group up assigning them to different roles. The next matter brought to light in the meeting was holding a funeral for Evon. As the other attendees agreed, Mzun said something which Namir could not understand, but the latter concluded that the vote was was in favor of holding a funeral.
Following Evon's subsequent funeral, Everi Chalis, a former Imperial governor who had since become an asset to Twilight Company, hosted another meeting to propose a new plan for the company. The campaign, named Operation Ringbreaker, would target a series of lightly defended imperial worlds before it's sole objective, the Kuat Drive Yards. According to Chalis, the fall of the shipyards orbiting the planet Kuat would be a crippling blow to the Empire's fleet production. As she finished her presentation, Mzun debated the tactics of the shipyard invasion with fellow soldiers Gadren and Carver. As Chief Medic Von Geiz asked for all those in favor to speak, only Mzun, Gadren and Quartermaster Hober remained silent, with the other Twilight members making the vote in favor of Chalis' plan.
The first target in Operation Ringbreaker was warehouse world Mardona III. Mzun was among the troops landed on the planet, who were tasked with planting thousands of ion mines along the tram network. When armored vehicles were reported to be sweeping the sectors around the tramways, Namir called all of the squads to cluster under a housing block. He intended to occupy the block and establish a fallback position. Mzun, Gadren and Sergeant Zab expressed their worries for the citizens living there, but Namir went along with the plan regardless. Thus, the squads sealed off the majority of the entrances to the housing block and set up defenses. Namir then established terms with the residents in order for them to be less of an obstruction to Twilight Company. After six days on Mardona III, they had completed their mission and were picked up by the Thunderstrike and Apailana's Promise again.
After Mardona III, Twilight Company fought two more battles as part of Operation Ringbreaker. The company then attacked the plastoid factories of Nakadia, where numerous soldiers fell casualty to bioweapons deployed by the Empire. Once their point of origin was located, Namir led a dozen aliens, including Mzun and Gadren to destroy the warehouse holding the toxins. They were successful, and Twilight Company subsequently won on Nakadia.
After three further battles, Twilight Company captured the Inyusu Tor mineral processing facility on the manufacturing planet Sullust. However, the Thunderstrike was shot down before it could pick up the company again, with the Apailana's Promise retreating with its X-wings. Now stranded, Twilight Company began setting up defenses at the Inyusu Tor facility. Although they were likely going to face an unbeatable army from the Empire, Mzun, Gadren, Namir and Carver pretended that the battle that they were to face was winnable. The Empire eventually attacked Twilight Company at Inyusu Tor, but lost when the Imperial II-class Star Destroyer Herald was sabotaged from inside and the ground forces were defeated below.
A non-human, Mzun was known to speak in a language different to galactic basic was outraged upon hearing news of possible deserters from Twilight Company. On Mardona III, the alien was concerned for the safety of the residents of a housing block when Hazram Namir intended to occupy the area. When Twilight Company was under threat of an attack at the Inyusu Tor facility, the alien chose to pretend to the other troops that the upcoming battle was winnable.
The Mzun appeared in Battlefront: Twilight Company, a novel written by Alexander Freed and published in 2015.