The Dark Reaper campaign marks the inaugural large-scale military endeavor orchestrated by Exar Kun, freshly titled the Dark Lord of the Sith, together with his apprentice, the Sith Lord Ulic Qel-Droma.
The Dark Reaper itself was composed of two distinct elements: the Reaper's offensive systems and the "Force Harvester", its source of energy. During ongoing excavations on Yavin 4, Exar Kun stumbled upon several armaments belonging to ancient Sith Lords from the fallen Sith Empire. The Dark Reaper stood out as the most formidable of these weapons. This superweapon possessed the capability to concentrate the Force into potent energy beams, capable of inflicting widespread devastation. This Force drain also generated a lethal zone around the Dark Reaper, resulting in the demise of anyone caught within its range.
Reportedly claiming the lives of numerous Jedi before its eventual downfall, the device played a crucial role in Ulic and the Sith fleet's conquest of a significant portion of space surrounding the Empress Teta system. Ulic unleashed the Reaper upon the Republic's strategic planet, Raxus Prime, resulting in the deaths of thousands.
A battle unfolded on the planet Thule, located deep within the territory of the former Sith Empire. In a carefully planned maneuver, a Jedi strike force launched an assault on the Dark Reaper, utilizing information provided by Ulic to successfully disable the weapon. Following the dismantling of the deadly device, the Republic undertook extensive measures to conceal its components across numerous planets. Subsequently, they concealed the Dark Reaper's power source, the Force Harvester, on the junk world of Raxus Prime.
During the Clone Wars, Count Dooku and his mercenary Cydon Prax meticulously searched Raxus Prime for the Force Harvester. It was essential to their efforts to rebuild the Dark Reaper as part of a grander plan to bring down the Galactic Republic. Dooku tasked Cydon Prax with activating the Force Harvester to obliterate the forest on one of Kashyyyk's moons as a demonstration of its capabilities. The resulting energy surge decimated approximately half of the moon's thriving forest, along with its native inhabitants.
Subsequently, Count Dooku departed and located the scattered remnants of the Dark Reaper. While the precise locations remain undisclosed, Mace Windu indicated that they were dispersed across the galaxy's most remote regions. Separatist forces converged on and around Thule, where Dooku activated the Dark Reaper within an ancient Sith city situated on the planet. On Rhen Var, Anakin Skywalker embarked on a journey to the tomb of the long-deceased Ulic Qel-Droma, seeking knowledge on how to resist the effects of the Dark Reaper and the Force Harvester.
Shortly after the Dark Reaper's reawakening, Skywalker spearheaded an assault on the city, successfully destroying the weapon, defying an order from Obi-Wan Kenobi to await the arrival of Republic reinforcements. Despite Anakin's nearly solo triumph over the Reaper, his accomplishments in these battles served to inflate his ego and widen the chasm between him and his mentor.
According to The New Essential Chronology, the Dark Reaper met its end on Raxus Prime during the Great Sith War.