Doctor Strange: 25 WTF Moments

I'm just about willing to accept that Mordo would be outraged at the Sorcerors' interference with the Natural Order of things and want to eradicate them, even if he would literally be dead and Dormammu would be the king of the universe if Strange hadn't, but I can't accept all of the post-credits stinger.

In it, Mordo appears and "punishes" Pangborn for his interference with the Natural Order by doing some sort of spell that takes away the magic that is making his spine work. It's Mordo's heel-turn cementing moment, and it's a great expression of his agenda to "cleanse" the Earth of the Sorceror problem.

Only, what the hell did he actually do to Pangborn? The film establishes that magic can be learned by anyone as long as they are able to open their mind to it, and that Pangborn channelled the magical energy of the multiverse to overcome his injury. So are we supposed to believe that Mordo just STOLE that knowledge? Or that he's somehow now capable of stealing other people's powers? Where exactly is the precedent for that?!