Fans are already bracing themselves for some major changes in the Marvel Cinematic Universe next year with the release of Avengers: Infinity War, which will be the final film for some favorites. But just how much will the showdown between Earth's Mightiest Heroes and Thanos shake the status quo? Co-director Joe Russo isn't saying, but he cautioned that audiences should be ready for "intense surprises."

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"My brother [Anthony] and I believe in stakes," he told MTV News at Comic-Con International in San Diego. "I believe that everything has to have an end at some point in order for it to have value. The audience should be prepared."

Marvel Studios President Kevin Feige sidestepped questions about the potential deaths of major characters, but said, "It'll be emotional for a lot of different reasons. As all our films try to do, we want to have the laughs, we want to have the heart, we want to have the humor, and Infinity War has all of that."

Directed by Joe and Anthony Russo, Avengers: Infinity War boasts a sprawling ensemble cast that includes Robert Downey Jr., Josh Brolin, Mark Ruffalo, Tom Hiddleston, Chris Evans, Chris Hemsworth, Jeremy Renner, Chris Pratt, Elizabeth Olsen, Sebastian Stan, Benedict Cumberbatch, Paul Bettany, Samuel L. Jackson, Cobie Smulders, Benedict Wong, Zoe Saldana, Karen Gillan, Vin Diesel, Dave Bautista, Pom Klementieff, Scarlett Johansson, Tom Holland and Anthony Mackie. The film arrives in theaters May 4, 2018, with the untitled sequel opening May 3, 2019.