In my world, the brain is a complex organ capable of more than just controlling the body. It's unique design allows it the ability to manipulate magic. Over time as the mind develops it will craft special nodes in the neural works of the brain that, when stimulated, can cast magic.
These powers are technically innate but evolve in certain directions over time. But you don't typically start out knowing these abilities. Instead you need to have your first stimulation, typically this occurs in a dream, but can be pushed into activation through mindful meditation. One can even choose how it evolves through rigorous meditative practices.
Almost anyone can have these powers.
Later in the future, humans design a form of hypnosis using spinning devices called fairy switches. These tools could be used to alter neural circuitry and reprogram the mind. Each fairy switch has pegs adorning the sides that form an irregular pattern. And a strange spiral symbol at its center. When these pegs rotate around the center piece, they create a hypnotic pattern that alters the brains neural pathways.
This allows for universal spells to be learned. Amd through this anyone, even those who still have dormant magic, can access these simple spells. However, doing this degrades the dormant nodes within the brain, making your Innate magic less potent.
When using fairy switches, the neural pathways are changed over time to allow for the use of magic without repercussions.
Another method, however, activates multiple neural pathways simultaneously. This allows the hypnotized to use magic without the training (for a short while), but the overstimulation is agonizing and sometimes even paralyzing.
These two fields of hypnotism are often pursued by psychologists and therapists.
Eventually, people also learned of demons. These are basically infected nodes that are tied to traumatic events in the user's past.
While these demons rarely affect the world around them, instead preferring to torment a single victim, there are demons strong enough to actively cast curses on the surrounding area.
Curses are typically the warping of perception. Almost like hallucinations that attach themselves to a person rather than induced by drugs. These hallucinations can be objects, entities, or environments.
Hypnotists also specialize in demons, though there are conflicting schools of thought on how to approach them. One is repression. A quick method that suppresses the demon within the person for a time, but never really deals with it. Then, there is extended care, where the demon is slowly unraveled over several sessions of hypnotic healing.
While innate powers are much less constrained, universal spells often have to do with the following.
Enhanced perception/ strength/ endurance: those who experience the proper hypnotic treatment can use their awakened mind to alter their body and mind significantly. Surviving poison. Supercharging organs or muscles. Slowing blood flow. Even having the mind process more information at a faster rate.
There is a group of individuals that learn to control their demons through meditation and elixirs. While their methods are effective, there are those who believe that to harbor a demon at all is evil.
Eventually, in the future humans design kindred spheres, tools that can replicate a brain and thus spells, but are modular enough to be changed on the fly and used much faster than a fairy switch. Meaning multiple spells can be cast from this device, so long as it has a scan of a brain in the first place.
However, due to how this technology works, only those who provided the brain scan can use the kindred sphere.