W.I.T.C.H. Season 2 P is for Protectors

The Guardians must save Meridian from the evil sorcerer Phobos and Cedric who are searching for Phobos' sister, the long lost princess of Meridian and true heir to the throne. They later find her and the Guardians then set about saving her from Phobos. When Meridian is freed from evil and true heir takes the throne, a new mysterious sorceress named Nerissa frees Phobos' top henchmen and reforms them as the Knights of Vengeance. Once the Guardians learn more about the sorceress and her evil plan of reuniting former Guardians, they are able to defeat the Knights only to have more powerful Knights, in addition to the former Guardians attack them.