The following contains major spoilers for Strange #3, available now from Marvel.
Marvel's latest Sorcerer Supreme is about to come face-to-face with the lethally twisted brother of Moon Knight -- Shadow Knight.
Strange #3 (by Jed MacKay, Marcelo Ferreira, Roberto Poggi, Don Ho, Java Tartaglia, and VC's Cory Petit) sees Clea lash out at the supernatural gang known as the Blasphemy Cartel in a horrifying fashion. After the cartel's recent attacks on the territory Clea has taken under her protection as the new Sorcerer Supreme of Earth, Clea eliminates over a dozen cartel members. This draws the attention of the cartel's enigmatic leader, Director None. Upon deciding that the threat of Clea is too detrimental to their own plans, Director None announces the authorization of a Lazarus Agent. Though this upcoming threat isn't referred to directly within the issue, the preview for Strange #4 points toward the Lazarus Agent being none other than the long-lost Shadow Knight.
First appearing in Doug Moench and Bill Sienkiewicz's "Nights Born Ten Years Gone" from the pages of 1979's Hulk! #17, Randall Spector was the younger brother of Marc Spector/Moon Knight. Although the two were close, Randall's quiet contempt for his brother and lust for power drove him to murder a woman Marc was romantically involved with. When Marc learned of what had happened, he hunted Randall down and very nearly killed him with a grenade. Randall later returned alongside his fellow CIA agent Sandahl Swarn, who would go on to cybernetically augment him. This transformed Randall into Shadow Knight, the even darker antithesis to Moon Knight. During a battle between the two in 2010's Shadowland: Moon Knight #3 by Gregg Hurwitz and Bong Dazo, Shadow Knight was killed by his brother, saving countless lives and fulfilling a promise to his patron god Khonshu in the process.
Clea first appeared in Stan Lee and Steve Ditko's "The Domain of the Dread Dormammu!" from the pages of 1964's Strange Tales #126. The daughter of the Faltine Umar and niece to Dormammu, Clea is a powerful sorceress in her own right. Her tumultuous relationship with Steven Strange eventually saw the two wed, though their matrimony would ultimately fall apart. During the events of Jed MacKay and Lee Garbett's Death of Doctor Strange, Clea returned to Earth and rekindled her relationship with the titular Sorcerer Supreme before his final passing. In the wake of Doctor Strange's untimely demise, Clea has taken up his mantle and quickly established herself as a much more serious threat than her husband was. Clea has also recently made her live-action debut in the Marvel Cinematic Universe in Doctor Strange and the Multiverse of Madness, as portrayed by Charlize Theron.
Strange #3 features cover art by Bjorn Barends and is on sale now from Marvel Comics.