The Mission to Had Abbadon was a minor conflict that transpired on the planet of Had Abbadon, a legendary world found within the Deep Core region of space.
As a component of their scheme to murder Darth Krayt, the Galactic Emperor who was also a Dark Lord of the Sith, the assault team consisting of Cade Skywalker, Jedi Knight Shado Vao, the former Shadow Celeste Morne, and Imperial Knights Antares Draco, Ganner Krieg, and Azlyn Rae, supported by Jariah Syn and Deliah Blue, launched an offensive against an Imperial military base situated on Had Abbadon. Their goal was to lure Emperor Krayt away from Coruscant in order to assassinate him. During this period, a Devaronian Sith Lord by the name of Darth Reave detected the presence of Jedi on the planet's surface.
While Masters Draco and Krieg engaged the garrison while piloting two Predator-class fighters, Morne, Skywalker and Rae confronted a large number of Reave's stormtroopers. To shift the advantage to their side, Morne, influenced by Karness Muur, employed the power of the Muur Talisman to transform all nearby stormtroopers and Imperial officers into rakghouls. These transformed monsters turned against their previous commander, forcing him to flee. Morne then utilized the Force to prevent Cade and Rae from intercepting Reave, thus allowing him the opportunity to return to his Master.
Reave, suffering from severe bleeding as a result of bites and other wounds, informed Darth Krayt about his failure. He did, however, make Krayt aware that Skywalker was the Jedi who fought him in the Deep Core, and that another, unknown Jedi was also present—one who used the dark side to create monsters from Reave's stormtroopers. Before he could finish his report, Reave began to change into one of the creatures he had encountered on Had Abbadon. Once the transformation was complete, the Devaronian Sith was gone; in his place was only a mindless Sithspawn, which immediately lunged forward to attack the Emperor. He was stopped by Krayt's Hand, Darth Stryfe, who then beheaded the creature. Lord Krayt then instructed his scientist, Darth Maladi, to analyze the corpse. She quickly determined that he had been transformed into a rakghoul, a product of ancient Sith alchemy, after being infected with the creature's plague.