We’re still pretty much in the dark concerning Sam Raimi’s Doctor Strange In The Multiverse of Madness outside of the additions of Elizabeth Olsen’s Scarlet Witch and Xochitl Gomez as America Chavez. The rest of the returning cast consists of Benedict Cumberbatch, Chiwetel Ejiofor, Benedict Wong, and Rachel McAdams.
One thing we do know that Loki head writer Michael Waldron worked with Raimi to rewrite the script from scratch.

Fans have spotted a listing on Mandy that Yenifer Molina is connected to scene that is expected to feature Namor villain Gargantos. This would be the most recent nod to Namor/Atlantis coming to the MCU and it would support the Namor tease that former director Scott Derrickson made on Twitter before deleting the post.
People have jumped to the conclusion that Molina is actually playing Gargantos, but the role simply says “Gargantos Fight 2” (looks like the name of a scene, not a character) and there is a strong possibly it’s simply a nameless extra role (looking at her other roles in her listings are extremely minor such as “officer worker” and “waitress”) that is fighting against or being attacked by the monstrous villain in an action sequence. Normally, Marvel hires motion-capture actors or bigger names to voice these types of CGI characters.
I wouldn’t be shocked if Molina is simply an extra during a visual effects heavy action scene.
There had been rumblings that Brother Voodoo and Clea would appear but those castings haven’t been made official by either trade reports or confirmations by Marvel. Outside of the return of Baron Mordo we don’t have an official villain despite previous teases of Nightmare being used by Derrickson.
I wouldn’t be shocked if we end up seeing Tom Holland’s Spider-Man appear given that Cumberbatch is confirmed for Spider-Man: No Way Home, but must have shot his scenes in London because he wasn’t spotted in Atlanta and the Doctor Strange 2 production overlapped with Spidey 3.
Doctor Strange In The Multiverse of Madness is set to be released on March 25, 2022.
SOURCE: MANDY