Doomsday will soon be upon us. On December 18, Marvel Studios will release its biggest film since Avengers: Endgame, if not its biggest film ever, with Avengers: Doomsday. And while official plot details remain under wraps, it's pretty clear that several different universes will be suffering through an incursion, where entire realities collide into each other resulting in the destruction of one or all of the universes involved. So far, it seems the main Marvel Cinematic Universe (Earth-616) will be colliding with the universe featured in The Fantastic Four: First Steps, as well as some simplified version of Fox's X-Men universe (which will finally give us comic-accurate costumes for the characters).