WARNING: This contains SPOILERS for Doctor Strange in the Multiverse of Madness.
Doctor Strange in the Multiverse of Madness' biggest cameo, John Krasinski as Mister Fantastic, set up what could be the MCU's next major multiverse threat. While the first Doctor Strange had already mentioned the multiverse concept, it was not until Loki that the MCU really started exploring the idea of different – yet similar – versions of the same character. With What If...?, Spider-Man: No Way Home, and now Doctor Strange 2, the multiverse is turning out to be to Phase 4 what the Infinity Stones' storyline was to Phases 1, 2, and 3.
Just like how Thanos wanted to weaponize the Infinity Stones, the MCU is slowly introducing characters that could be a danger to the multiverse by either trying to interfere with it or control it. The first major one was Kang, who was not in Multiverse of Madness, following the introduction of He Who Remains in Loki. In Doctor Strange in the Multiverse of Madness, powered by the influence of the Darkhold, the now-villain Scarlet Witch became the multiverse's most urgent threat, willing to inhabit other peoples' bodies and cause incursions in the process. Doctor Strange 2 also revealed that Earth-838 Doctor Strange ended up causing an incursion while trying to harness the powers of the Darkhold, which shows just how exposed to threats the multiverse is.
Related: Doctor Strange In The Multiverse Of Madness Ending Explained (In Detail)
With Scarlet Witch dead, presumably, and every Darkhold in the multiverse destroyed, it would seem that the stability of the multiverse is safe, at least until Kang's plans begin to come to fruition. However, Doctor Strange in the Multiverse of Madness' Reed Richards cameo teased
Read more on screenrant.com