The Clone Wars S03E13: Monster

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. Talzin has Asajj secretly select a warrior from the distant Nightbrother village: Savage Opress. With the power of dark magic, Talzin transforms Savage into a hulking warrior ultimately loyal to Asajj. She then delivers Opress to Dooku, where he will serve as his secret Sith apprentice in a plot to overthrow Darth Sidious.