The Mission to Rattatak offered Count Dooku an opportunity to discover a new ally, one powerful enough to overcome the Jedi.
In the year 22 BBY, Dooku journeyed to Rattatak, specifically to the Cauldron, a combat arena. His objective was to locate an assassin for the CIS. While there, he observed a mysterious warrior, who skillfully used the Force and her lightsabers to defeat every opponent in the arena. This warrior introduced herself as Asajj Ventress, a Sith warrior. Dooku, disputing her claim of being a Sith, challenged Asajj to a duel and emerged victorious. He argued that she possessed fear, a trait he believed was absent in true Sith, thus disqualifying her. Enraged by this assertion, Ventress attempted to kill Dooku, but he incapacitated her with Force lightning.
After a period of unconsciousness, Ventress awoke to find her lightsabers placed on a nearby table. Dooku unexpectedly confronted her, initiating another duel. Ventress used Force Jumped and grabbed her lightsabers. The battle commenced, fueled by their mutual animosity. Dooku mocked Ventress, suggesting that a true Sith would have swiftly defeated him. This taunt ignited Ventress's anger, causing her to attack recklessly. Ultimately, Dooku pulled her lightsabers from her grasp and chopped them in half, securing his victory.
Impressed by her capabilities, Dooku introduced Ventress to Darth Sidious, who observed them via hologram. He then assigned Ventress a critical mission: to assassinate Anakin Skywalker. Ventress, after receiving Komari Vosa's lightsabers, departed in a Fanblade starfighter with the intent of eliminating him.