Originating during the Clone Wars, the Confederacy of Independent Systems was working on their Ultimate Weapon, a project which would later be turned over to the Galactic Empire, and converted into the Death Star project.
In 19 BBY, Supreme Chancellor Palpatine sent the 501st Legion of clone troopers to Mygeeto. The official story was that the unit was sent to support the Galactic Marines under Ki-Adi-Mundi by destroying an energy collector. In truth, the unit was sent to retrieve an energy crystal used in one of the InterGalactic Banking Clan's power generators that was necessary for the Hammertong project. General Mundi was suspicious of the unit's activities, but clone marshal commander Bacara convinced him to let go of his phantom fears. 
By the time that the original Death Star was entering service in 0 BBY, the Hammertong project, now led by a scientist named Eloy, was already working on a superlaser design for the second, even more powerful battlemoon. A prototype section of the prime weapon was constructed in a secret facility on Gorno, and when the research base was relocated to another planet, the Hammertong was installed for transport in a massive hold aboard a specially-adapted Strike Cruiser.
In 0 BBY, a scientist from the Hammertong project named Kellering approached a Mistryl Shadow Guard team led by Manda D'ulin about providing security for the prototype during transit. Ostensibly, Kellering claimed that Eloy was skeptical about the capabilities of Captain Drome's security detail, but when he brought Manda to the base to meet Eloy, they were attacked by stormtroopers and Manda was gunned down, followed shortly thereafter by her comrade Pav D'armon.
The four surviving Mistryl responded by attacking the Imperials, determined to leave a message that the military could not simply shoot down Shadow Guards as they pleased. Shada D'ukal and Karoly D'ulin stole the Strike Cruiser, blasting out of orbit even as an Imperial Star Destroyer arrived to guard the prototype.
The Mistryl escaped to Tatooine, where they hid the stolen cruiser beneath the sands of the Dune Sea, and Shada and Karoly headed into Mos Eisley, disguised as the Tonnika Sisters, to find a freighter that could transport part of the weapon back to Emberlene. They made contact with Rebel Alliance agent Riij Winward, but quickly fell out over whether details of the Hammertong should go first to the Shadow Guard or the Alliance. The Mistryl ended up with their freighter, but Winward stole their astromech Deefour, along with a technical readout of the device - promising politely to return it once the Alliance had acquired the information.
It can be assumed that Deefour subsequently delivered the readouts to the Rebellion, while the Mistryl took their component back to Emberlene; but is unknown what happened to the Hammertong project team including Kellering and Eloy, or to the cruiser abandoned on Tatooine.
Behind the scenesEdit
- Star Wars: Battlefront II
- Death Star (Mentioned only)
- Hammertong: The Tale of the "Tonnika Sisters" (First appearance)
- Specter of the Past (Mentioned only)
- Star Wars Encyclopedia
- The New Jedi Order Sourcebook
- The Complete Star Wars Encyclopedia
- The Essential Atlas
- The Essential Guide to Warfare