As Strange's mentor, she will play one of the most powerful mystics in the Marvel Universe, something she said she couldn't turn down, since she's a fan of Marvel herself.
"I just really liked the premise of this and the idea of playing this character. I'm a Marvel fan and I think this particular world that Doctor Strange goes into is really, really, really exciting," Swinton said. "I'm really interested as both an actor and a fan to see what's done in this particular world. It's all about creativity. It's not about everything exploding at the end. It's about something very different. The idea of playing The Ancient One is really just too tickling. I can't say no to that!"
She added that in spite of her reputation for doing a lot of prestige/indie/arthouse movies, she wasn't at all worried about being drafted into upcoming Marvel sequels and was curious what shape, if any, that might take for her character.
Doctor Strange will be out in November 2016. You can keep tabs on it and all the other upcoming comic book movie releases here.