I was a bit surprised that Cumberbatch was listed in the cast as the Necromancer... I know that he fills both this role and was cast as the voice of Smaug but when did the Necromancer appear? In the scene where the Witchking came back to "life"?
Yes, in that scene Radagast sees the Necromancer, or at least some manifestation of it. How could you have missed that?