WARNING: This article contains spoilers for Marvel's "Doctor Strange," which opens Friday in North America.

Following the release last week of "Doctor Strange" in the United Kingdom, details have begun circulate about the plot of the Marvel Studios film -- including an appearance by another of the Sorcerer Supreme's oldest foes. Now, ahead of the film's U.S. premiere, a new promo offers a fleeting glimpse of the otherworldly villain.

Hosted by star Benedict Cumberbatch, the video introduces viewers to "The Multiverse," a concept that of course plays a central role in the reality-bending Marvel Studios film. "There are dangers, yes, but wonders, too," he says, "And power -- so much power -- and in the wrong hands, anything can happen."

REVIEW: "Doctor Strange" Fails to Live Up to MCU Standards

It's there, at about the 40-second mark, the image of Mads Mikkelsen's Kaecilius gives way to a set of enormous eyes, belonging to Dormammu, aka the Dread One, one of the most powerful mystical beings in the Marvel Universe, and a recurring adversary of Doctor Strange.

As director Scott Derrickson confirmed last week, Cumberbatch pulled double duty on the film, playing both Stephen Strange and, thanks to motion-capture technology, Dormammu, who's summoned by Kaecilius.

"We knew it was an all-CG character, but as we were in production Benedict brought it up as an idea," the filmmaker recalled to IGN. "He said, 'What would you think about me doing it?' I said, 'Let me think about it, you know.' It's an interesting idea, because I did fancy the idea that as this other-dimensional being he's not moving through the Dark Dimension, with a countenance, with eyes and a face, eyes and a mouth, and a human visage – why would he? He takes that form on to communicate with Strange."

Opening Friday nationwide, "Doctor Strange" also stars Chiwetel Ejiofor, Rachel McAdams, Benedict Wong, Michael Stuhlbarg, Benjamin Bratt, Scott Adkins and Tilda Swinton.

(via ComicBook.com)