While the Marvel Cinematic Universe is populated with many benevolent sorcerers, occasionally one turns their back on the pack to fulfill their own agenda. In Doctor Strange, that was Mads Mikkelsen's Kaecilius, who led a group of zealots in an attempt to overthrow The Ancient One and her mandates. He tried to accomplish this by tapping into the power of Dormammu, and a deleted scene from the movie shows the first time he and his followers trying to contact the ruler of the Dark Dimension.
For those who need a refresher on Doctor Strange, the movie began with Kaecilius and his followers breaking into Kamar-Taj to steal a spell from the Book of Cagliostro. This deleted scene from Marvel shows what happened afterwards, with Kaecilius and a few of his followers gathering around to make contact with Dormammu. One of the Zealots reasonably questions if this is safe, as he's concerned about if Kaecilius has deciphered the Cagliostro spell correctly. Kaecilius brushes his concern away, noting that they won't be the ones "knocking"; Dormammu will. As the main antagonist and his followers chant the spell, a symbol quickly forms on each of their foreheads. Well, almost of all of them. Nothing happens to the zealot who questioned Kaecilius, and evidently not happy that one of his minions wasn't bequeathed the power because he didn't have the proper faith, Kaecilius cuts down the man with a conjured blade.
While the above scene does shed some light on how Kaecilius and his followers initially tapped into Dormammu's power, the final cut of Doctor Strange was able to convey this effectively enough later on with a follow-up ritual that cracked the skin around all their eyes, but imbued them with the necessary power to defeat The Ancient One and other Masters of the Mystic Arts. What they didn't count on was a former surgeon with a knack for learning magic ridiculously quickly getting in their way, but there are some things that even magic can't predict.
Like many fictional villains, Kaecilius didn't see himself as evil in Doctor Strange, instead channeling dangerous powers for the greater good. Dissatisfied with the way The Ancient One policed traveling to other dimensions, thus preventing humanity from being immortal, he sought to help his fellow people by channeling Dormammu's power, the same power that The Ancient One used to extend her lifespan. While Kaecilius was successful in eventually killing The Ancient One, in the end, not only did Stephen Strange prevent him from completely accomplishing his goals, but the good Doctor also outwitted Dormammu himself with the Time Stone. Not bad for a first day on the job.
Doctor Strange will be released on home media next Tuesday, February 14, and the Blu-ray/DVD release will follow on February 28.