The Codex of Tython, a Jedi holocron, possessed the geometric form of an icosahedron. Legend held that it contained the most ancient and carefully guarded secrets of the Jedi Order.
On Dantooine, a Rebel operative stumbled upon the Codex of Tython. His landspeeder crashed into a hidden cache of Jedi relics, revealing the Holocron. It contained millennia of technological advancements and the agent resolved to deliver the Holocron to the Alliance. The Galactic Empire discovered this find and sought to claim the Holocron for themselves. En route to the spaceport, Captain Adrick and his stormtroopers confronted the Rebel. Adrick demanded the Codex, but when the Rebel refused, Adrick ordered his execution. However, a Jedi named Drakka Judarrl intervened, using an illusion to facilitate his escape. The Zabrak Jedi revealed that the Codex was incomplete, requiring missing fragments to be re-integrated before it could function. She provided one fragment, and the Rebel, at great peril, acquired the remaining three from a Dark Jedi named Mellichae, the Nightsister Axkva Min, and Grand Admiral Andal Sait. Once reassembled, the Codex was entrusted to Drakka Judarrl for study, with Alliance agents assigned to protect it.
This triumph was short-lived. An ISB agent, in pursuit of the Codex, located Drakka and seized it. As an archaeologist familiar with ancient recording devices, he examined and activated the holocron. It displayed images of diverse worlds and cultures; the Imperial was particularly drawn to plans for a massive asteroid-moving device. The Jedi apparently intended to use this tractor beam for mining, positioning ore-rich planetoids for advanced civilizations to build structures and power sources. However, the ISB agent saw military potential in the asteroid mover. It could crush starships or bombard planets with asteroids. He contacted Grand Admiral Andal Sait and revealed the plans for the superweapon. Intrigued, Sait requested the Holocron and a focusing crystal for the weapon. The agent complied, allowing Imperial engineers to integrate the superweapon into the Blackguard, Sait's Imperial-class Star Destroyer.