After 37 films, the Marvel Cinematic Universe (MCU) needed an antidote to "superhero fatigue".
In the past few years, the franchise has experienced a run of lukewarm reviews and sporadic success, and a messy split with an actor who'd held a key role.
After testing potential cures, bosses scoured the MCU's vast source material and summoned villain Doctor Victor von Doom as the focus of its future.
Avengers: Doomsday, where he'll make his full debut, will show whether the superhero universe can still attract more casual cinemagoers alongside devout fans.
But who has enough star power to lift a series that has accumulated a box office total of more than $30 billion (£26bn) worldwide?
Robert Downey Jr.
He was "the one person who could play" the role, according to bosses when they introduced him on stage at San Diego's Comic Con in 2024.
The reveal sparked ear-splitting celebrations from the audience in the room.
Having played Iron Man Tony Stark in 10 films, Downey Jr is a guaranteed draw for many, with his signature character's trilogy alone making more than $2.4bn (£1.7bn) around the world.
But critics saw re-casting him as a different character as a sign of those in charge running low on ideas.
Getty ImagesAs for who's joining Downey Jr in Doomsday, it's almost easier to name an A-lister who isn't involved, such is the vast length of its call sheet.
Chris Evans, Chris Hemsworth, Pedro Pascal, Tom Holland.
Florence Pugh, Hayley Atwell, Letitia Wright, Vanessa Kirby.
(Excuse us while we take a deep breath.)
Sir Patrick Stewart, Sir Ian McKellen, Benedict Cumberbatch, Channing Tatum.
You get the idea.
As Doomsday teasers drop, momentum and speculation build for the MCU's next big thing, due to land in cinemas on Friday 18 December, with a sequel scheduled for the following year.
So what do we know so far?
Warning: The following contains what anyone who isn't up to date with the MCU might consider to be spoilers.
'Will Return' teasers
Such is the hype around Doomsday's teasers, their "will return" endings have become a meme.
First came confirmation that Chris Evans' Steve Rogers "will return".
BBC