Avengers: Doomsday officially kicked off production not long ago after announcing its cast via a chair stunt that had millions of people on pins and needles for hours. While there were some shocking announcements, like Channing Tatum’s return as Gambit and Fox X-Men stars like James Marsden coming back for another adventure, the first name attached to star in the film was Robert Downey Jr. Marvel announced at San Diego Comic-Con last year that Avengers: The Kang Dynasty had been reworked to Avengers: Doomsday, and Downey Jr. would return to the MCU to play the titular villain, Doctor Doom. With production now in full swing, Downey just shared the best look at himself behind-the-scenes of Doomsday, and it seems the former Iron Man actor has been hitting the weights in preparation to take on The Avengers.