MCU Phase 4: 10 Biggest Mysteries (So Far)

As of this writing, there have only been two movies in Phase 4. While Black Widow didn't do much in the way of setup, Shang-Chi did quite a bit. It teased the origins of the Ten Rings, it hinted at a deeper relationship between Wong and Abomination, it set up a Ten Rings series (if the rumors are to be believed), it turned Bruce human again, and then there's this: the Ten Rings were calling out. To whom or what?

In the film's mid-credits scene, Wong, Captain Marvel, and Bruce tell Shang-Chi and Katy that the Ten Rings are sending out some sort of beacon. They don't know the recipient of said beacon, but they're beckoning to something. They're connected to the Dweller-in-Darkness, but we don't know if the Dweller is supernatural, à la Doctor Strange, or if he's just a cosmic being that's perceived as supernatural. As such, the nature of the Rings could be anything.

The fact that three separate Avengers - each with their own area of expertise - felt compelled to get involved points to the Ten Rings playing a major role in the MCU's future. Clearly the Avengers see them as a problem, and someone is coming. We can expect that someone (or someones) to play a major role going forward.