How much of Robert Downey Jr. are we actually supposed to see? That's where Avengers: Doomsday faces one of its biggest creative challenges. Instead of audiences watching Doctor Doom, they'd be watching Robert Downey Jr. playing Doctor Doom. Those philosophies couldn't be further apart, and Avengers: Doomsday needs to make that clear. Marvel has undoubtedly spent a lot of time thinking about this while developing Avengers: Doomsday, but execution is everything.