My magic system may seem a bit disjointed at first, compared to some other magic systems that you may be used to. There are a handful of magical tropes that I play with and alter, a few I take out and make their own thing, and still others that I discard entirely. Gone, for instance, is the seemingly ever-present divide between psionics and magic - psionic powers exist in my setting, but simply as an expression of magic and not as something distinct and separate.
The three major ways to use magic also, while differing in their execution, have clear and intentional lines of overlap. Wizardry is more scientific, channeling is more natural, and divine magic is more creative and ephemeral. However, all three tie into and tap the same substance, the same power, the same drive and the same force - the natural ability of the fey to alter the material world through the power of dreaming.
It is well established that only godtouched, fey, and certain artificial creations like monsters, undead and constructs can use magic. However, all creatures that have living souls have their own magical essences. The auras discussed in the previous post are an imprint of the soul, a representation of the energies of the dream plane, replenished whenever a soul dreams. While a soul's aura is only visible to the naked eye while using magic, it is always there.
Further, either through the fey's presence on Aarn for so long, as some side effect from the end of the war of the gods, or through a fundamental property of the astral sea bonding with the material plane, material objects that aren't alive also seem to have their own magical essence. It is far less dramatic than the essences of living souls, but important enough to be used in spellweaves and rituals none the less. This could simply be the objects affecting magical energies from other, living sources - similar to how a rock in a stream will create eddy currents, but the effect is largely the same regardless.
The essences themselves have consistent patterns to them. A rock of a certain shape, element and size will always produce the same signature. A plant's leaf, bat droppings, even a hand-made carving of a specific kind of wood will displace, radiate and resonate with auras in predictable ways. These patterns can be brought out and represented visually by simple, abstracted patterns called runes. Importantly, each individual sentient soul has its own unique rune, a self-representing symbol that never changes, and is in fact a permanent identifying characteristic of that soul's unique self. These personal symbols tend to be used in Aarnian society as signatures and are often used as identification, and as the focuses for scrying spells.
Runes are used by both divine casters and by wizards. They can be etched into physical objects or tatooed onto flesh to create permanent or semi-permanent magical effects. They can be used by wizards and divine spellcasters both to create scrolls - a physical storage of a single casting of a certain spell (though this is far more common with wizards than with divine spellcasters). They are also used by wizards in their spellbooks as a magical shorthand, the runes representing which material components are required for a spellweave, alchemic potion or elemantic construct.
Despite this flexibility, runes are somewhat limited. When they are used in the case of scrolls to cast a stored spell, they are not only destroyed but they tend to physically damage whatever they were written on. When they are used for permanent or semi-permanent effects, the effects only last as long as the runes remain intact, are always active in the mean time. Destructive effects on weapons usually require a very resilient scabbard, for instance. Importantly, the runes also cannot create any spell effects more complicated than simple channeler powers.
This does mean that while characters with magical tatoos can impersonate channelers, their magic's effects are not as easily controlled, not as flexible, and cannot be turned on and off, making them poor impersonations at best.
A step up from using runes is directly using the material components that the runes represent. All branches of wizardry - spellweaving, alchemy and elemancy use material components directly, and rituals are the branch of divine magic that uses them. There is also a magical technique called infusion that allows crafters to put material components directly into the construction of an object. This allows the object to have more permanent, more easily controlled, and more complicated spell effects than rune crafted objects. Due to this the technique of infusion is largely preferable to rune crafting, but both kinds of enchantment have their uses.
The most raw and direct method of using magic however is easily some of the other methods of divine casting. Manifestations, incantations, chants and songs, and chants and songs that also involve dancing are the four methods of casting divine spells outside of lengthy and costly rituals. Divine spells are learned permanently and do not need to be prepared, but they do use up an exhaustible supply of power which must be replenished by dreaming. It is a more powerful and dramatic method of casting than any wizardry effects, but it is also much less flexible.
Channeling, of course, has already been discussed in depth. It is the natural way in which godtouched creatures can use magic, and a character is either born with it or he/she is not. One important aspect of channeling, that I don't believe I've mentioned in previous posts, is that while all channelers have elemental affinities, all non-channelers do as well. Similar to aura color, a godtouched's elemental affinity is considered an astrology-like predictor of personality in Cerenbaun society. In fact, it can easily be treated as their direct counterpart to our own astrology. The study of elemental affinities is a personality-based pseudoscience with much more detail and expectations than the behavioral traits associated with simple aura colors. I may or may not develop an astrological system based on the 14 elements, but this is a low priority considering some of the other things I have to work on in the near future.