Marvel Studios has released the first proper trailer for Avengers: Doomsday as tickets go on sale, offering the clearest look yet at returning characters including Thor, Steve Rogers and Robert Downey Jr's Doctor Doom. The footage matters because it hints heavily at the film's central threats and stakes, showing an "incursion" (a collision between universes) endangering the heroes and prompting Doctor Doom's cryptic opening narration about an "unthinkable decision" to come.

The trailer moves from Xavier's School, where Professor X and Doctor Doom appear during the incursion, to Avengers Tower, where Thor delivers a rallying speech warning that "we're going to need a miracle." It brings together an enormous ensemble, including the Fantastic Four, Ant-Man, Bucky Barnes, Sam Wilson's Captain America, the Thunderbolts, Namor, Shuri, X-Men characters and more, with several heartfelt farewell moments suggesting heavy losses ahead. In the climax, Thor is unable to hurt Doctor Doom even with Stormbreaker, prompting the surprise return of Chris Evans's Steve Rogers, who summons Mjolnir to prove his identity, leaving unanswered questions about Doom's true role and how Rogers returns.