"Cydon, activate the Harvester once I've taken off. When it has destroyed the forest, exterminate the remaining Wookiee population. I want no survivors." "Yes sir."
At the Battle of Thule, Prax guarded the Reaper in the ancient Sithcity of Kessia as the Jedi-ledclone army assaulted the Separatists' position. The Chistori soldier ultimately perished in battle during a firefight with the Jedi Anakin Skywalker. Shortly after Prax's death, Skywalker single-handedly destroyed the Dark Reaper and brought an end to the crisis that nearly brought about the defeat of the Republic and their Jedi defenders.
As Dooku's newest bodyguard, Prax was entrusted with the execution of several missions that the Count regarded as important to the Separatist cause. Prax was also charged with taking custody over the young Boba Fett, an unmodified clone of Jango Fett that the latter raised as his son. However, Prax failed to be an effective substitute for the orphan's lost father.[2]
Once the Force Harvester was fully reconstructed on Alaris Prime, a forest moon that orbited the planet Alaris in the Kashyyyk system, Cydon Prax activated the device on the order of Count Dooku, who wished to see its effects on Force-wielders like Skywalker. Prax then vacated the entire area soon after the Harvester's activation, given that it was designed to kill every living being within close proximity. Despite this, Skywalker managed to escape the weapon's blast radius with the aid of Bera Kazan, a former Separatist mercenary who aided Prax in locating the Harvester shortly before being betrayed and used as a test subject for the machine.[1]
Count Dooku, Cydon Prax's employer
The crisis came to a head at the Battle of Thule, just as Count Dooku and Cydon Prax oversaw the completion of the new Dark Reaper superweapon. In the midst of a firefight between Republic clone troopers and Separatist battle droids, Prax entered the battlefield in his personal Dreadnought battle tank. Although he destroyed Mace Windu's TX-130 Saber-class fighter tank, the Jedi Master survived his vessel's destruction and continued to lead the Republic forces on the front line. Meanwhile, Prax regrouped with Dooku in the ancient Sithcity of Kessia, also the capital of Thule where the Dark Reaper was held.[1]
When Anakin Skywalker led a division of clone units into the city while piloting his own TX-130 tank, Count Dooku ordered Cydon Prax to confront and kill the young Jedi shortly before departing the planet. Thus, a firefight began between the Prax and Skywalker and ended with the latter's victory and the destruction of Prax's Dreadnaught battle tank, ending the Chistori mercenary's life as the Republic went on to claim victory on Thule after the destruction of the Dark Reaper.[1]
Cydon Prax was known as a callous, dispassionate being and a lethal soldier on the battlefield. His pitiless demeanor affected his ability to raise Boba Fett in Jango Fett's place, making him an unsuitable father figure.[2] It also left him desensitized to mass murder as he felt no compunction about utilizing the Force Harvester's lethal energies on Alaris Prime, a moon filled with numerous specimens, including Wookiee settlers. His utter lack of ethics also rendered him unconcerned with acts of treachery, such as when he betrayed and imprisoned Bera Kazan shortly after she aided him in the Separatists' search for the Force Harvester.[1]
In addition to his skills as an elite trooper[2] and marksman,[1] Cydon Prax was a talented pilot[2] who could compete in battle with highly-skilled Jedi such as Mace Windu and Anakin Skywalker.[1] Due to his Chistori biology, Prax was a cold-blooded reptilian; a fact that contributed to his reputation as a mercenary who possessed a "heart of ice."[2] His other physical features included square teeth and a crown of horns that adorned the base of his skull.[4]
During the Clone Wars, Cydon Prax wore a fully-encased suit of armor, much like his predecessor Jango Fett, that concealed his alien appearance. Though Prax's armor was not of Mandalorian design, its most prominent feature was a left shoulder-mounted blaster. Other assets in the armor's design included a system that maintained Prax's body temperature in a constant state in any environment.[2]
In Boba Fett: Crossfire, Prax is described as having a crown of horns and square teeth. No other known Chistori exhibits these traits. Cydon Prax also does not have a large snout like Desann, given that the shape of his helmet reflects a human-like skull.