Walt Disney Pictures unveiled the first trailer for Oz: The Great and Powerful at San Diego Comic-Con 2012 earlier today. James Franco stars as Oscar Diggs, a shady circus magician from Kansas who is transported to the magical land of Oz, where he manages to convince Ozians that he is a powerful wizard. However, the witches Theodora (Mila Kunis), Evanora (Rachel Weisz) and Glinda (Michelle Williams) are not so convinced of his greatness. Take a look at the first footage from director Sam Raimi's highly-anticipated adventure.