3. Imperius Rex
During the final battle of Civil War, as both hero and villain wage war on the city streets to decide the victor once and for all, the momentum seems to be in the hands of the pro-registration crew. Captain America is fighting valiantly while being ganged up on by a group of villains, including Lady Deathstryke and Venom (both of whom are properties of other studios), when it seems all is lost. Suddenly a cry of "Imperius Rex" is shouted as King Namor and an army of Atlanteans join the fray in aide of the anti-registration heroes. It's a huge game-changer and allows Cap's crew to regain the upper hand. Unfortunately, while Marvel may have technically regained the rights to Namor (a fascinating character with the potential to be a huge hit onscreen), there are apparently still some legal hang-ups which currently prevent him from appearing in a Marvel film. It's a shame because his impact in the story will be sorely missed. It's an awesome moment that the movies need.