Matt Damon celebrated his 46th birthday by presenting a trailer for his new film The Great Wall at New York Comic Con.
The Hollywood star revealed footage from the big-budget period epic in which he plays a soldier in ancient China battling evil creatures.
"Ultimately it's a monster movie," he told the audience at Madison Square Garden.
"Monsters are attacking the Great Wall and we all defend it. It's historical fantasy. I'd never really done that before."
Director Zhang Yimou was previously forced to defend his decision to cast Matt in the lead role. It came after Constance Wu, star of sitcom Fresh Off The Boat, claimed that the film perpetuates the "racist myth that (only a) white man can save the world".
Matt did not address the controversy directly but said: ""It just felt very exciting to incorporate Chinese mythology into a big Hollywood sword-and-sandal epic. It's unlike anything I've ever seen."
Matt also revealed a text message his father had sent him on his birthday about Republican presidential candidate Donald Trump.
He told the audience: "It said: 'Happy birthday my boy. My birthday present to you is letting you know that in exactly one month we can kiss Trump goodbye... Now that's not a bad birthday present. I doubt you'll get a better one. Love you. Dad'.
Matt added: "Let's leave our walls to the movies. Although, you have to worry, if he did get elected that Mexico might actually put up a wall to keep him out."
The Great Wall is set to be released in UK cinemas on February 24.