Sam Raimi continues to fill out the cast of his Wizard of Oz prequel Oz, The Great and Powerful, as Mad Men actress Abigail Spencer is the latest to sign on. The impressive cast now includes James Franco as the charismatic magician, Mila Kunis, Rachel Weisz and Michelle Williams as three witches, and Zach Braff as Oz’s faithful assistant. The story tells the origins of the eponymous Wizard, as Franco’s character is whisked away in a hot air balloon to the land of Oz, where he must team up with Glinda the Good Witch (Williams) in order to battle her evil counterparts (Kunis and Weisz) who are bent on taking over the land.Heat Vision reports that Spencer will play a willing participant in Franco’s magic show while he’s performing in Kansas. On Mad Men, Spencer played the foxy Miss Farrell, schoolteacher to Don Draper’s kids and the focal point of Mr. Draper’s super serious bedroom eyes in season three. Oz, The Great and Powerful begins filming in Michigan later this month. We recently reported that Raimi will be reteaming with composer Danny Eflman for the fantasy tale. The film hits theaters March 8^th, 2013.