When the (former) Sorcerer Supreme and America Chavez travelled to the 838 Universe in Doctor Strange in the Multiverse of Madness, they encountered a group of Multiversal heroes(?) known as The Illuminati. The Scarlet Witch ultimately ended up making short work of all but one of them (Mordo escaped), but they remain one of the most talked-about aspects of the sequel despite only appearing in a couple of scenes.
One of the more surprising additions (for those who avoided the leaks, at least), was Black Bolt, with Anson Mount reprising his role from the now defunct Inhumans TV series. The powerful Inhuman leader met arguably the most brutal end out of all of his teammates, but managed to make quite an impression thanks to his comic-accurate costume (and hilariously gruesome death).
Now, thanks to a new "Constructing the Multiverse" featurette that's included on the movie's home media release, it's come to light that Black Bolt's outfit was entirely CGI!
Several shots in the featurette show Mount wearing a full mo-cap suit, while most of his Illuminati castmates (there's no sign of John Krasinski as Reed Richards) appear to be in practical get-ups. Marvel Studios movies often contain examples of slightly dodgy VFX, but Black Bolt's costume looks pretty damn flawless.
As for why this particular suit was a CG creation, it's possible Mount joined the production later than the others and the wardrobe department simply didn't have time to put something practical together.
In Marvel Studios’ Doctor Strange in the Multiverse of Madness, the MCU unlocks the Multiverse and pushes its boundaries further than ever before. Journey into the unknown with Doctor Strange, who, with the help of mystical allies both old and new, traverses the mind-bending and dangerous alternate realities of the Multiverse to confront a mysterious new adversary.
Doctor Strange in the Multiverse of Madness stars Benedict Cumberbatch, Chiwetel Ejiofor, Elizabeth Olsen, Benedict Wong, Xochitl Gomez, with Michael Stühlbarg, and Rachel McAdams. The film is directed by Sam Raimi, and Kevin Feige is the producer. Louis D’Esposito, Victoria Alonso, Eric Hauserman Carroll and Jamie Christopher serve as executive producers. The screenplay was written by Michael Waldron.
The Doctor Strange sequel is now streaming on Disney+.