India, April 18 -- T he trailer for Marvel's next Avengers film, Avengers: Doomsday, was unveiled at CinemaCon in Las Vegas on Thursday. Slated for a December release, the film marks Robert Downey Jr.'s return to the MCU, this time as villain Doctor Doom, not Iron Man. The trailer sets up Doom's arrival and hints at the return of the original Avengers. Downey Jr and Chris Evans, who played Steve Rogers, took the stage to unveil what's being called the Trailer of Doom, offering the first look at the Russo Brothers' comeback to the franchise. Though the trailer hasn't been released publicly, reports say it received loud applause at CinemaCon, prompting Downey Jr to request a replay. Thor leads the charge against Doom, reflecting on fallen Avengers, but is easily overpowered. In a surprise moment, a voice calls out "Hey, pal!", revealing Evans' Steve Rogers, who lifts Mjolnir as Thor looks on in disbelief. Speaking at the event, Downey Jr. said he hadn't imagined returning to the MCU in a new role, while Evans added he agreed to return only because the story offered a compelling reason for Steve Rogers' comeback. HTC...