I’m always interested to see all of the rules set behind magic in comic books, but a lot of the time there doesn’t seem to be a well defined system at work.  It seems any scrub off the street could take down some pan-dimensional demon as long as they had the right mystical artifact, or spoke in a goofy manner, or had an enchanted body part of Agamotto.  One of the best scenarios involving this type of sorcery was when Mr. Fantastic received an enchanted set of what appeared to be brass knuckles from Dr. Strange that shot magic whenever Reed admitted to not knowing how the things worked.