The clip opens with a voice-over from these heroes talking about the "idea" that was to bring remarkable superheroes together to create something greater - aka the Avengers Initiative.
From that point on, it's all out chaos and action.
Up to this point, Marvel Studios has released 17 films dating back to 2008's "Iron Man," with five more coming in the next couple of years. "Infinity War" is poised to feature all of the heroes fans have grown to love over the last decade, including Captain America, Spider-Man and more.