Marvel StudiosMuch like Endgame was the culmination of the MCU’s multi-phase Infinity Saga, Doomsday and its sequel, Secret Wars, are the concluding chapters of the franchise’s six-year-long Multiverse Saga. After Endgame ushered in major status quo changes with the departure of Chris Evans and Robert Downey Jr. (both of whom are now returning), it wasn’t immediately clear what direction the MCU would be taking next. Eventually, projects like Spider-Man: No Way Home and Dr. Strange in the Multiverse of Madness widened the scope of the series by introducing the Multiverse, a concept that’s provided an equal number of headaches and genuinely intriguing stories since it became a staple of superhero comics.After confirming the Fox X-Men have their own specific universal designation in Deadpool and Wolverine and introducing a separate universe containing the Fantastic Four in First Steps, the first Doomsday trailer gave us a glimpse at what’s in store when worlds collide later in December. There’s no better time than now to revisit the crucial installments of the Multiverse Saga, considering each is a stepping stone to the multidimensional cataclysm that seems to be facing Marvel’s many characters. However, one MCU project in particular serves as a key to the convoluted roadmap of canon Doomsday is smashing together, and that project is Loki.When the buddy-cop show first started, there was no way to predict that it would become one of the MCU’s most important projects. | Marvel StudiosWhat Happened In Loki?When Loki was announced, there were a lot of questions regarding how a TV spin-off would work for a character who’d just been knocked off three years earlier. The show quickly answered this question in the first episode — the Loki we follow is a variant from the year 2012 who stole the Tesseract during the Avengers’ time-traveling infinity stone heist in Endgame, and his escape with the cosmic cube created a short-lived alternate universe. That universe was destroyed and our new Loki was captured by the Time Variance Authority, an organization that exists outside of time and space with the goal of “pruning” alternate universes created by unplanned branches from the MCU’s central Sacred Timeline.The first season of Loki revolved around Loki being recruited by a TVA agent named Mobius to help capture a vengeful female Loki variant going by Sylvie, and culminated in the reveal that the TVA was created by a version of Kang the Conqueror known as He Who Remains, in a last-ditch effort to end a multiversal conflict started by his villainous counterparts. The plan worked, but only as long as the TVA continued to prune alternate timelines from existence. Sylvie, who was orphaned when the TVA destroyed her original timeline, gets revenge by murdering He Who Remains, an act that inadvertently causes the creation of the Multiverse by removing the TVA’s guiding hand.Season 2 explored the consequences of Sylvie’s choice, revealing that the increasing number of branching universes was putting immense pressure on the Temporal Loom, a device created by He Who Remains to preserve the Sacred Timeline’s structure. While Loki and his allies initially attempt to adjust the Loom to compensate for the burgeoning Multiverse, they inevitably discover that the Loom is incapable of scaling to accommodate infinite alternate universes and is in danger of a meltdown. With no other options, Loki sacrifices himself and becomes a new version of the Temporal Loom, bonding with the Multiverse into a tree-like structure that can sustain the sudden appearance of countless alternate universes.Despite saving the Multiverse and the TVA with his actions, Loki’s sacrifice still doesn’t stop the threat of the incursions. | Marvel StudiosHow Does Loki Tie Into Avengers: Doomsday?Sylvie’s actions in Loki’s first season quite literally birthed the Multiverse into existence, and Loki’s choice at the end of Season 2 crystallizes it into a somewhat harmonious balance, allowing for the co-existence of the X-Men and the Fantastic Four’s universes alongside the mainline MCU. But just because Kang the Conqueror seems to have been written out of the MCU’s plans, that doesn’t mean the Multiversal cataclysm he warned about ceases to exist — on the contrary, the trailer for Doomsday seems to hint at the threat of an incursion, when two universes collide with each other and annihilate both. Loki’s brief appearance in the Avengers: Doomsday trailer seems to imply that his role as the new Temporal Loom will be crucial to the film’s plot. But that importance could take many forms: he and the TVA could be monitoring the impending threat of the incursions, or his existence as the connective tissue of the Multiverse could be linked to Doctor Doom’s efforts to remake the timeline as he sees fit, if the film is setting up for a loose adaptation of Jonathan Hickman’s 2015 Secret Wars arc. With only five months between now and Doomsday, a crash course on the specifics of the Multiverse Saga seems like it’ll be a necessary undertaking, and a rewatch of Loki just might be crucial to understanding what exactly is at stake when Doom finally arrives.Avengers: Doomsday releases on December 18, 2026. Loki is streaming on Disney+.