Avengers: Infinity War and Avengers: Endgame were among the biggest, most complex films ever made, involving storylines and characters from over two decades of Marvel movies. Not every scene that was filmed made it to the final product. During a watch party for Infinity War, writer Stephen McFeely tweeted a picture from the movie where Doctor Strange is decked out in Iron Man's armor.
The photo reveals Benedict Cumberbatch standing next to Robert Downey Jr., the two placed in front of a green screen as they gaze incredulously at something to the left of the camera. Doctor Strange is wearing the Iron Man armor while wearing a unitard over his lower half. This is the set up that Downey Jr. traditionally wore, with the VFX effects team adding the rest of the Iron Man armor to his body in post-production.
The picture is a part of a scene that takes place aboard the spaceship of Thanos' right-hand alien Ebony Maw. Doctor Strange had been captured and imprisoned on the spaceship, where Maw was torturing him into giving up the Time Stone placed in the locket around Strange's neck.
Iron Man and Spider-Man also board the ship to rescue Strange. In the deleted scene, Tony allows Strange to wear his armor so the Wizard can use it to escape from his prison. Even though this version of events was filmed, it was eventually cut in favor of showing Iron Man and Spidey working together to distract Maw and send him hurtling out of the ship to his doom.
If this scene had stayed in the movie, it would have been the second instance of a hero using Stark tech to battle enemies. Bruce Banner used the hulk buster armor during the battle in Wakanda when his inner hulk refused to come out. Perhaps it was because of the similarity between the two scenes that the filmmakers decided to cut Strange's scene in the Iron Man suit.
The meetup between Doctor Strange and Stark had been hotly anticipated by fans, given the similar nature of the two characters, and the fact that the actors behind both the superheroes had also both played the role of Sherlock Holmes.
The movie did not disappoint in this regard. From their initial sniping at each other, to developing a grudging respect for the other, to Strange sacrificing his life to save Tony, to Tony ultimately sacrificing his own life to enable Strange's plan to stop Thanos, to the Doctor kneeling down in respect in front of Tony's deceased body, the relationship between the two characters had amazing ebbs and flows in the midst of everything else that was going on.
While Iron Man is seemingly done with the MCU at this point, Doctor Strange will return in the WandaVision Disney+ show, and his own solo sequel film, where the Master of the Mystic Arts embarks on an exploration of the multiverse. Who knows, he might encounter a different version of Tony Stark in one of the alternate realities.