Star Wars: The Clone Wars (2008): 3x14

Witches of the Mist

Anakin and Obi-Wan, sent to track down the mysterious figure behind the deaths of several Jedi, soon find themselves on the trail of the monstrous apprentice that Ventress has created: Savage Opress, who has been trained in the ways of the Sith by Dooku. When Opress returns to Count Dooku after an unsuccessful assignment, Ventress strikes. With Opress at her side, she attacks Dooku. Opress’ loyalty is fleeting, however, and Dooku and Ventress discover that this new apprentice has a will of his own. When Savage returns to Mother Talzin, she gives him a new task: To seek the Outer Rim for his long-lost brother….