Star Wars: The Clone Wars - Season 4 Episode 19 -

"Massacre" After failing to kill Dooku or control Savage Opress, Asajj Ventress is advised by Mother Talzin to reject the ways of the Sith and rejoin the Nightsisters. Upon discovering Ventress' location, Dooku commands General Grievious to launch a droid assault in a bid to eliminate Ventress and wipe out Mother Talzin along with the entire Nightsister clan. As Ventress and Grevious square-off in saver combat, Talzan creates a voodoo doll of Dooku to figuratively kill him whilst her relative Daka - the eldest of the sister's clan - awakens an army of undead Dathomirian Nightsisters to hold off the droid forces. Ventress defeats Grievous just moments before getting wounded, forcing her to escape the chaos alone as the rest of the Nightsisters are all eventually massacred; Grievous went to proceed in killing Daka, whereas Talzan escapes as her success in finishing off Dooku is ultimately foiled. The episode closes with the green misty 'spirit' of Mother Talzin bidding farewell and good luck to Ventress, who is now left to grieve for her sisters and lament her lost future.