This article contains spoilers for Defenders #1.
Marvel's Doctor Strange has revealed how he can beat any sorcerer in the comic universe. When Doctor Strange became Sorcerer Supreme, he swore an oath to defend his plane of reality from any threat. It is an oath he has taken seriously, even indulging in the darkest arts, like magical cannibalism in order to defeat the forces that would otherwise overwhelm or consume this dimension.
Doctor Strange is secretly Marvel's darkest hero. As Sorcerer Supreme, he confronts powerful extradimensional entities such as Dormammu and Shuma-Gorath. Meanwhile, envious mystics who covet his title and powers seek him out, attempting to prove they are Strange's superior. The life expectancy of Sorcerers Supreme really isn't all that great, and most of them don't tend to survive long. But in Defenders #1, by Al Ewing, Javier Rodriguez, and Alvaro Lopez, Doctor Strange reveals he has a trick up his sleeve to give him an edge in combat.
In the issue, Doctor Strange's Sanctum Sanctorum is infiltrated by a mysterious figure called the Masked Rider. Believing the Masked Rider to be a potential threat, Strange uses the a particular spell - cantrips of the Onyx King - to generate a field that means neither sorcerer can use magic, or any power not contained in their own bodies. That spell uttered, he switches to the last tactic a rival would expect - martial arts, which he has learned well.
This is a remarkable spell, and it should give Doctor Strange an advantage against almost any potential assailant. Granted, it wouldn't be much use against someone like Doctor Doom - master of science as well as sorcery - but most others would be taken aback by it. What's more, unlike the MCU, where the Masters of the Mystic Arts all practice martial arts as part of their training, in the comics, few mystics have cultivated such skills.
The cantrips of the Onyx King are conceptually similar to the magical runes used by Agatha Harkness in WandaVision, which prevent any sorcerer other than the one who cast them using their power. It is possible Stephen Strange will find himself on the receiving end of those same runes in Doctor Strange in the Multiverse of Magic, because in the MCU, Wanda is now learning magic from the forbidden book of magic called the Darkhold - a book that can exert a corrupting influence. If he does, though, Doctor Strange wouldn't find himself quite so vulnerable as the Masked Rider in Defenders #1 - because, as, in the comics, he has his martial arts to fall back on.