'Avengers: Doomsday' Trailer: Marvel Studios' promotional plans for Avengers: Doomsday faced a setback with the premature leak of its fourth trailer. The clip surprisingly showcased a crossover between Black Panther and the Fantastic Four, featuring Shuri, Namor, and M'Baku, rather than the anticipated Doctor Doom confrontation. This leak has intensified fan anticipation for the film's December 2026 release.