This Inconvenience writer has found that making a person doubt himself can be the most powerful magic in the world.
The writer notes that it is not necessary that the client believe in magic; it is enough to plant the seeds of self doubt and to encourage the belief that the client deserves this doubt.
Vulgar magic, indeed.
How to Begin with a Seeker
Practice the Great Magic of doubt.
Believe that he deserves his fate.
It is not essential he believes in the occult,
a supply of doubt is an absolute and vulgar magic.