This review contains spoilers for episode 9 of What If...?.

After spending the whole first season of What If...? promising not to get involved in Earth’s affairs, the finale episode sees the Watcher breaking that oath and interfering in humanity’s problems. “What If... The Watcher Broke His Oath?” follows on from the cataclysmic events of last week’s episode as Ultron’s possession of the Infinity Stones threatens the fabric of the entire multiverse.

In order to prevent a full multiversal meltdown and the end of life as we know it, the Watcher assembles his own Avengers team from previous What If...? episodes – Captain Carter, Star-Lord T’Challa, Party Thor, etc. – to form the Guardians of the Multiverse. Not only did this provide the welcome return of many fan-favorite variants from the series; it also gave the finale episode a sense of conclusiveness and finality that isn’t often seen in anthology series.

RELATED: Marvel Studios' What If...? Episodes Were Longer Prior To COVID-19

It can be difficult for an anthology show to feel like a complete, cohesive work because they explore new characters and storylines every week. But “What If... The Watcher Broke His Oath?” truly feels like a finale. The whole season has been building toward this. The anthology format usually results in movies and TV shows that aren’t equal to the sum of their parts, but this one pulls together all the previous stories for a thrilling climax.

The Watcher in the What If finale

The finale episode offers the kind of action-packed superhero adventure that What If...? has largely avoided in favor of character-driven storytelling. The Watcher sends the Guardians of the Multiverse to a barren, uncharted planet to discuss their battle strategy, then Thor instantly attracts Ultron’s attention, eliminating the element of surprise. From there, the rest of the episode is an all-out battle between superhero variants and their cybernetic overlord. The animation has a few vibrant visual flourishes like the breathtaking use of super slow-motion in the most crucial action beats.

Just like last week’s Ultron-centric episode, the What If...? finale makes Ultron the formidable threat he should’ve been on the big screen. This version of the character, dubbed “Infinity Ultron,” has all the capabilities of the indestructible A.I. that Tony Stark and Bruce Banner designed, but with the added cosmic power of the Infinity Stones. The spectacle of multiple heroes fighting one unstoppable baddie for the Stones in the rubble of a destroyed planet is reminiscent of the Battle of Titan from Infinity War.

Doctor Strange in a bar in the What If finale

Killmonger’s betrayal was pretty predictable – why would the Watcher recruit a cold-hearted murderer with delusions of grandeur to join his lifeline superhero squad? – but his acquisition of the Stones did present an interesting moral quandary for the team. The right thing to do would be to just get rid of the Stones so no villain like Thanos or Ultron could ever use them to take over the universe again, but Peggy is tempted at least for a moment when Killmonger suggests she could use them to return to Steve.

A few characters are underutilized. The version of Gamora that managed to singlehandedly defeat Thanos and claim his double-bladed sword in her universe barely has any lines or screen time in this episode. Plus, it would’ve been fun to see more of Ultron’s fight with the zombified Wanda Maximoff. But, granted, the show only has a half-hour runtime. To fully explore this storyline and all the characters involved could take a few hours. Still, the characters that do get a spotlight – Captain Carter, Star-Lord T’Challa, post-apocalyptic Natasha Romanoff – enjoy plenty of memorable moments.

Gamora with Thanos' sword in the What If finale

It’s possible that the Thanos-killing Gamora is being primed for a larger role in the future. The finale’s mid-credits scene teasing that the Steve from Captain Carter’s universe is still alive suggests that her story is far from over and will continue into season 2. It seemed that every episode of What If...? would focus on a new universe, but A.C. Bradley and her team of writers have taken a more flexible approach to the show’s premise. The series has been building up a roster of recurring characters that Marvel fans look forward to revisiting – and the finale brings them all together in the same timeline for a classic MCU team-up.

Overall, the first season of What If...? has been pretty up and down. Some episodes, like “What If... T’Challa Became a Star-Lord?,” truly explored an alternate scenario and the huge ramifications one small difference can have, while others, like “What If... Captain Carter Were the First Avenger?,” were little more than a condensed remake of an MCU movie with a different character in the titular hero’s place.

Doctor Strange and the Watcher in the What If finale

Fortunately, with “What If... The Watcher Broke His Oath?,” the season has gone out on a high note. By establishing Doctor Strange’s friendship with the Watcher and teasing the return of the Hydra Stomper, the season 1 finale has set up even wilder, more experimental multiversal adventures for next year.

MORE: The Common Thread Of What If...? Might Just Be Grief