With Avengers: Doomsday arriving in theaters on December 18, 2026, now is the perfect time to make sure you are fully caught up on one of the most ambitious and complex storylines Marvel Studios has ever told. The Multiverse Saga has been building across dozens of films and Disney+ series, and while you certainly do not need a PhD to enjoy Doomsday, knowing the key concepts will make the experience that much richer. Consider this your friendly guide to everything you need to know before you sit down in that theater.
What Is the Multiverse Saga?
Marvel’s Phases 4, 5, and 6 make up what is called the Multiverse Saga. Starting with WandaVision all the way back in 2021, the MCU has been slowly expanding the idea that our heroes’ universe is just one of an infinite number of realities. Every choice creates a new branch, every interference in time ripples outward, and the consequences of all that meddling are finally coming to a head in Doomsday.
The TVA and the Sacred Timeline
One of the most important things to understand is the Time Variance Authority, or TVA. This mysterious organization was originally set up by a character called He Who Remains to maintain what he called the Sacred Timeline, essentially the one “correct” version of reality. His entire operation was about pruning alternate timelines before they could grow and cause chaos.
In Loki Season 2, everything changed. When He Who Remains was killed, the multiverse was set free. Loki himself stepped up in an extraordinary act of sacrifice, restructuring the entire multiverse into a tree like formation resembling Yggdrasil from Norse mythology. That tree is almost certainly going to play a major role in Avengers: Doomsday, and understanding it helps explain why so many different versions of so many different characters may be showing up.
Nexus Events
A Nexus Event is simply a moment that causes a new timeline to branch off from the main one. The clearest example is when Loki stole the Tesseract during the time heist in Avengers: Endgame, creating an alternate version of events. Every major act of time travel or reality interference can create one of these, and as you will see below, that matters a great deal going into Doomsday.
Absolute Points
Introduced in What If…?, Absolute Points are events that simply must happen within a timeline or that reality begins to collapse and die. They are fixed moments in time that cannot be undone without catastrophic consequences. Doctor Strange learned this the hard way when he tried to save Christine Palmer and watched his entire world unravel as a result.
Anchor Beings
Deadpool and Wolverine introduced another key concept: the Anchor Being. Some individuals are so fundamentally important to their own timeline that if they are removed from it or killed, the whole reality begins to fall apart. Wolverine from Earth-10005 is the most prominent example. This concept is important because it raises enormous questions about which heroes in Doomsday might be Anchor Beings and what that means for the safety of their worlds.
Incursions: The Big One
This is arguably the most important concept to understand going into Avengers: Doomsday. An Incursion occurs when multiversal travel or interference becomes so severe that two universes literally collide, with the destruction of one or both being the result. Doctor Strange in the Multiverse of Madness introduced this terrifying concept, with one Doctor Strange variant’s reality being destroyed as a consequence of his actions.
Here is where it gets really interesting. Many fans and analysts believe that the time travel events of Avengers: Endgame, particularly Steve Rogers going back in time to live out his life with Peggy Carter, may have set off a chain of Incursions that are finally coming due in Doomsday. The chickens, as they say, may be coming home to roost.
From Kang to Doctor Doom
Originally, Jonathan Majors’ Kang the Conqueror was positioned as the Multiverse Saga’s central villain. After Majors’ departure from the MCU, Marvel made a bold creative pivot. Kevin Feige confirmed that replacing Kang with Doctor Doom had actually been in consideration for quite some time. The result is one of the most exciting casting announcements in Hollywood history: Robert Downey Jr. is returning to the MCU, not as Tony Stark, but as the iconic Victor Von Doom. The Russo Brothers, directors of Avengers: Infinity War and Endgame, are also back to helm Doomsday and its follow up, Avengers: Secret Wars.
A Doctor Doom with multiverse level power and a Robert Downey Jr. performance behind the mask is a genuinely thrilling proposition.
What to Expect in Avengers: Doomsday
Based on everything the trailers and official materials have revealed so far, Doomsday appears to bring together heroes from across multiple realities to face Doom’s threat. We have seen classic Avengers, X-Men characters, and variants of beloved heroes all seemingly converging for what promises to be the biggest Marvel event since Endgame. The Incursion concept appears to be front and center, and with the multiverse tree Loki built potentially at stake, the scale of what is coming is genuinely enormous.
If you have kept up with the Disney+ series alongside the films, you are in great shape. If you have not, the most essential viewing before Doomsday is Loki Seasons 1 and 2, Doctor Strange in the Multiverse of Madness, and Deadpool and Wolverine. Those four titles cover virtually every major multiverse concept you will need.
Avengers: Doomsday opens December 18, 2026. I cannot wait.
You May Also Enjoy: Disney Releases Official Watch List to Get Ready for Avengers: Doomsday Before It Hits Theaters
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