WARNING: The following contains spoilers for What If...? Season 1, Episode 9, "What If... The Watcher Broke His Oath?," streaming now on Disney+.

What If...? has shown fans many new and exciting aspects of the Marvel Cinematic Universe. Imagining that a cosmic swashbuckler could change Thanos' mind about universal genocide through sheer discourse is a compelling insight into not only the Mad Titan's strength but also his underrepresented intellectual curiosity. Showcasing Ant-Man's abilities in a lethal context as opposed to a comical one reimagines him as an upper-tier Avenger as opposed to someone who just made it in the door during a recruiting emergency. The films only tease at how powerful Doctor Strange can be and his episode opens up potential avenues to explore in his upcoming adventures across the multiverse.

"What If... The Watcher Broke His Oath?," however, is the best episode of the season and absolutely integral to future storytelling in the MCU. It unifies What If...?'s narrative, displays some of the most breathtaking action sequences and alters the paradigm of the entire Marvel endeavor.

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Infinite Ultron is incredulous that the Guardians of the Multiverse wont die

The MCU's greatest achievement is the seamless integration of its various intellectual properties into one overarching dramatic tale of good versus evil that includes characters who feel honest to their source material and resonate emotionally with audiences who only have a passing familiarity with them. It might have been simpler to design What If...? as a series of standalone installments that had no bearing on one another with unlimited creative freedom, but the decision to tell a cohesive narrative fulfilled the unspoken promise that each window into another reality truly mattered.

Furthermore, each of the multiverses shines in their debuts earlier in the season, but every one of them hits peak magnificence at some point in the final episode. Star-Lord T'Challa uses sleight of hand to pluck an Infinity Stone off of Ultron's chassis. Doctor Strange replicates a unique artifact of the gods, Mjolnir, and wields it in a hail storm of enchanted hammers. Killmonger's cursory examination of Ultron's carapace gives him enough technical familiarity to wrest the Stones from him. Captain Carter vaults herself repeatedly at a galaxy killer and catches a ride back to terra firma on the one true Mjolnir, not to mention her key assist to Black Widow. Natasha, in a character-defining moment, pulls off a shot so impressive, it makes Hawkeye look like an amateur.

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Strange Supreme battling Infinite Ultron in What If

Even amongst the heroes, one truly gets his due. When Strange Supreme, devourer of souls, destroys his universe and dooms himself to an existence of solitude, the idea of redemption and service to a greater good is not something he can imagine. As he serves Thor a beer behind haunted eyes, there is a pathos present despite the light-hearted environment. Later, Ultron designates Strange as the true threat, elevating him to a power level on par with extra-dimensional beings like the Watcher and Infinite Ultron himself. Each episode of What If...? delivers memorable iterations of beloved characters in incredible circumstances, but this is the only one capable of collecting them all into a satisfying whole that demonstrates the upper limits of the sum of its parts.

Loki opened the doors to the multiverse, with an endless amount of realities serving as a canvas for artistry. What If...? takes that seed and helps it bloom, serving as a precursor for the next phase of films. Doctor Strange in the Multiverse of Madness takes on a different expectation now that the first season has concluded, and this particular episode shows the amazing possibilities that the multiverse provides.

To see the epic conclusion, all episodes of What If...? Season 1 are now streaming on Disney+.

KEEP READING: A What If...? Guide: News, Easter Eggs, Reviews, Recaps, Theories and Rumors