Star Wars: The Clone Wars Season 3 Episode 13

When Count Dooku calls upon the Nightsisters seeking a replacement for Ventress, she and her kin seize the opportunity to exact revenge. Ventress visits the far side of Dathomir and the males of the planet seeking the most brutal and powerful warrior among them. Through their witchcraft, the Nightsisters transform Savage Opress into a monstrous killer designed to turn on his new master.