Dark Reaper campaign The Dark Reaper campaign was the first extended campaign by the newly christened Dark Lord of the Sith Exar Kun , and his apprentice , the Sith Lord Ulic Qel - Droma . History . The Dark Reaper weapon itself consisted of two separate components : the Reaper ' s weaponry and the " Force Harvester " which powered it . After continued excavation on Yavin 4 , Exar Kun chanced upon several weapons of the ancient Sith Lords from the defeated Sith Empire . The most powerful of these weapons was the Dark Reaper . This superweapon had the power to focus the Force into beams of energy to cause massive damage . This sucking of the Force also created a type of death threshold around the Dark Reaper which killed anyone within range of it . Great Sith War . Apparently claiming a great number of Jedi lives before it was defeated , the device aided Ulic and the Sith fleet in capturing a large portion of space around the Empress Teta system . Ulic unleashed the Reaper on the Republic staging planet of Raxus Prime , killing thousands . However , Ulic didn ' t entirely agree with Kun ' s plan , as he still had cared for several of the remaining Jedi — which included his brother , Cay Qel - Droma and his former lover Nomi Sunrider . Wishing to spare their lives , Ulic secretly revealed to the Republic the way to resist the Dark Reaper ' s effect , thereby allowing the Jedi forces to disable , rather than destroy it . The final battle was fought on the world of Thule , deep within the old Sith Empire . In a calculated strike , a Jedi task force staged an attack on the Dark Reaper and using Ulic ' s information , were able to disable the weapon . Breaking the deadly device apart , the Republic made great effort to hide the pieces on a myriad of different planets . They then hid the power source of the Dark Reaper , the Force Harvester , on the junkyard world of Raxus Prime . Clone Wars . During the Clone Wars , Count Dooku and his mercenary Cydon Prax scoured Raxus Prime for the Force Harvester . It was vital in the quest to reconstruct the Dark Reaper as part of the greater scheme to destroy the Galactic Republic . Dooku instructed Cydon Prax to activate the Force Harvester to destroy the forest on one of Kashyyyk ' s moons as a test of its power . The wave of energy killed roughly half of the thriving forest on the moon , along with its indigenous population . Count Dooku then departed and discovered the remnants of the Dark Reaper . The exact locations are not mentioned , but Mace Windu mentioned that it was separated into the farthest reaches of the galaxy . The Separatist forces congregated on and around Thule , where Dooku activated the Dark Reaper in an ancient Sith city on the planet . On Rhen Var , Anakin Skywalker journeyed to the grave of the long - dead Ulic Qel - Droma for information on how to withstand the effects of Dark Reaper and Force Harvester . Shortly after the revival of the Dark Reaper , Skywalker led an attack on the city , destroying the weapon , disobeying an order from Obi - Wan Kenobi to await Republic backup forces . Despite Anakin ' s almost single - handed defeat of the Reaper weapon , his feats in these battles served to fuel his ego and create an even greater personal rift between himself and his master .