Introduction and Workings of Magic

Magic entails the manipulation or activation of mana energy, a type of energy intrinsic to Life for as long as its inhabitants can remember. The most used definition, however, is the physical alteration of the world using mana as resource. Most living beings have a connection with this energy, yet a select few species are able to consciously manipulate it.
Creatures who can use magic are called mages or casters, creatures who passively use magic for their bodily processes are called magical creatures. There are far more magical creatures than there are mages on Life.

Mana and mana pools

Mana energy and its source

Mana is a type of energy that sets Life apart from our own world. It has the ability to transform into other types of energy, for example heat, kinetic energy, or even matter if packed densely enough. It also has the ability to move said energy from one point to another. It's known to radiate off of some matter, but the earth itself is known as the most important source of mana energy through a mechanism not well understood.
The manipulation of mana central to magic requires the correct organs to be present inside a creature. The most important organ is named the glamra and acts like a magnet for mana energy, drawing it towards the body and directing it parallel to the nerves and veins. The energy doesn't literally flow through the body, but gravitates to the nerves and veins like an object caught in a planet's orbit. The more energy the glamra has been saturated with, the weaker it becomes at attracting new energy until at its capacity it stops at a hard cap. When the body spends or releases the energy it can once again be attracted. The glamra has been known to constantly renew the mana energy of the body, creating a flow with the environment.

The three main organs aren't a rare occurrence, but a large majority of the creatures with this organ lack the functionality to cast magic, be it because of having an incomplete glamra, being unaware of how to cast magic, or failing to activate the necessary processes. The organs are most common in mammals and are considered a mutation, but demons have them by default. In mammals the glamra is found between the stomach and the liver, located in the center of the body. Several other organs exist with an unknown function, one ventral of the heart named the ertra and one in the prefrontal cortex named the stamsra, and all three organs lie on the medial axis of the body. -Curator

Mana pools

Every body comes with its own natural mana capacity, which can be trained to become larger and more efficient. The combination of a creature's capacity and speed of charging is called the mana pool. When evaluating a mana pool, quickness refers to how fast the pool recharges, width refers to its capacity, and size to the total package. Quickness varies between slow, median, and fast. Width varies between narrow, median, and broad. Size varies between small, median, and large. Slow mana pools recharge slowly, broad mana pools have a large capacity, and small mana pools have a low capacity and recharge speed, to give a few examples of terminology used.
Since the mana pools people are born with are laughably small, one of the largest challenges for beginning mages is to expand their pool to become large enough to allow for consistent training. It can take up to several months to expand the pool to such a strength that it allows for visible spellcasting, and it can take up to a year to become large enough to allow for consistent training without having to wait for enough mana to recharge. Enlarging the mana pool starts out slowly, then picks up its pace around a lower median size, and eventually slows down again as it gets to an upper median size.

Naturally, the mana pool is inactivated and somewhere in life activates. The glamra always attracts mana energy, but only the body's autonomic nervous system can use it in bodily or passive processes if the mana pool is inactivated. Once it is activated, it can be used by the somatic nervous system for active processes as well, which in most cases means in spellcasting. What triggers the activation of the mana pool is unknown; in some it's active from birth, in others it never activates. Once activated it remains activated, unless someone who knows what they're doing uses the correct technique to inactivate it again. This condition is referred to as gutlock or heartbane.
Most of a mage's training comes down to learning how to access and control their mana pool. First and foremost that means expansion and increase in recharge speed, but it also ties into how quickly the mage can direct already attracted mana into spellcasting, how good their grasp on their mana is, and estimating how much mana they have left.

Spellcasting

Manipulating mana

For spellcasting, mammals rely on the basic principle of redirected mana energy: their nerves. Because so many nerves are found parallel inside the arms and legs, wrists and ankles and by extension hands and feet are the place where all the action happens. The spine and the brain are also viable targets, but because of their internal location risk damaging organs if used as an output and is practiced only be advanced mages.
Casting magic requires a lot of experience to develop a feel for how to manipulate mana energy. There's very little theory linked to the first steps of spellcasting, and it all comes down to having a good teacher who knows what to focus on when bridging the gap between a completely new caster and a caster who can actually cast magic. It's like learning how to use a muscle you've never used before, and because it relies on discovering its workings at random with very little indication of whether you're going in the right direction, the pace at which a new caster develops their feel for mana varies wildly.
Once the mage has a decent grasp on how to cast magic, it relies on their thoughts. Magic is a response to a stimulus, just like the contraction of a muscle is, and the mage can consciously use it as they please.

Making it useful

To use mana energy is one thing. To cast it in a useful way is so radically different, it can take many years to go from mastering the one to mastering the other.

The manipulation of mana is still a tool, no other than flint and steel are to make a fire. Like there are endless ways to hold a rock, examine it, feel it, rotate it, drop it, throw it, and bash something with it, there are endless ways to direct mana energy. What decides how strong a mage is depends entirely on how well they understand the material they are manipulating, how fine their touch for mana energy developed, which patterns they send their mana energy into, and how creative they are.
As a result, there aren't spells that are set in stone. If a mage wants to create a fire storm around them, there's plenty of techniques to do so and they'll need to understand which steps they have to take to actually make a fire storm happen. Magic favours those who are creative and understanding enough in their school to find specific uses no one else thought of that put them ahead of the curve.

Schools of magic

Mana can be used to interact with different levels of energy. Pure mana energy is finer than heat energy, which is finer than matter. All of these are an expression of kinetic energy to a different degree. Whether the mage uses their mages to move their target energy, or to create it from mana energy is up to them and makes for two different casting styles.
The Grand Mavomare College created a system of nine schools to make learning them easier: fire, frost, wind, water, earth, light, darkness, life, and death. The schools are divided into four larger categories based on what energy is used and how it's used: heat-based, matter-based, mana-based, and application-based.

Emblems by ElithianFox

Heat-based: fire and frost

Fire and frost magic aims to manipulate the world based on the heat of its components. Fire magic centers heat in a selected area, frost pushes it away from the area. They have an intrinsic connection to objects aligned with their school, so fire mages can move warm objects through heat and frost mages cold objects through lack of heat. Fire mages thrive in warm environments that already have a lot of heat, but they can also create their own heat. Same for frost mages and cold environments. This is unrelated to the matter-based schools, as the state of matter doesn't limit them, but gases are easier to move than liquids, which are again easier to move than solids.
The schools were named after their most visible effect, but necessary components are still necessary. Many fire mages carry on them something to ignore so that they can create flames, and frost mages need a liquid to create ice. Learning to cast it for a large part requires the mage to learn not to burn themselves and to discover the various ways of transferring heat (convection, conduction, radiation) and moving objects. Over time, they develop a resistance to their own heat class they produce, but they'll always be susceptible to injuries if not careful.
One of the largest unexpected dangers is that the mage draws upon their own body's heat for casting. Fire mages are at risk of pulling all heat out of their body when channeling it to their wrists, thus risking dying from hypothermia. On the contrary, frost mages need a place to push all the heat away to when creating cold areas and risk overheating or even incinerating their own body if they're not careful enough about allocation. For this reason, many fire mages are well dressed while frost mages show a lot of skin.

Matter-based: wind, water, and earth

Wind, water, and earth mages move the most densely compacted type of energy, namely matter. They do so based on the state of matter; wind mages move gas particles, water mages liquids, and earth mages solids. There is a large overlap between the three schools, as objects can be in between states or be part one and part the other. This also means that there's a small overlap with fire and frost mages: wind mages have a better time in warm environments where gases flows more freely, while water mages prefer an intermediate environment and earth mages a colder one. Unlike frost mages, earth mages' materials can't be too cold, or they're hard to pull apart and use in casting.
Pushback is a limiting factor for matter-based mages. Pushing forward air, the air pushes back just as hard on the body, but not nearly as much as water or earth will. Using mana as driving force behind the movement makes the pushback much smaller than it would be were the body to manually move the matter, but it's still one of the biggest hindrances. Wind mages will want to be more agile to mitigate the soft push or air, yet possess enough strength to withstand the pushback of air This pushback is often used to glide, fly, or shoot up in the air and land safely. Water mages are an intermediate form, making for good swimmers and fairly athletic casters. Earth's resilience requires the strongest casters, often drawing highly athletic powerhouses to withstand its magnificent push.

Mana-based: light and darkness

Light and darkness magic focus on the core of magic: mana energy itself, untransformed and inactivated. Instead of changing mana energy from its primal form to another form of energy, they manipulate it raw and use its natural dichotomy as a source of power. Light mages tap into highly charged mana energy and transform their own body's mana into the charge they desire. Darkness mages do the same with lowly charged mana energy.
Every creature has a natural mana charge to their body, coming down to light or dark based on how high its total charge is. Mana-based casters draw upon that charge, so a caster's species largely determines which of these two they will become. A dark creature doesn't have to change their natural mana's charge to cast darkness magic, but has to take a great risk for their body trying to transform a dark charge into a light one. It is possible, but it isn't very safe and risks damage.
The goal for a mana-based mage is to learn how to transform their charge into a wide spectrum, without changing dark mana energy from light and vice versa. By changing their charge, their own body becomes the negative of that change. For example, if a dark creature wants to cast 100% charged darkness from their 50% charged body, their body will become higher in light charge than before. The charge deposits its positive components into the body to become more negative. Bringing a body out of its natural charge is comparable to making it more acidic, and if taken too far this can create injury, even death. It should be noted that mana energy of the opposite charge, for example 50% light and 50% darkness, will dissipate when combined in equal quantities.

Many cultures tie a morality to these two schools. Demon societies tend to think darkness is the purest form of energy, human and angel societies revere light. It should be noted that despite these cultural notions, there is no absolute morality tied to either of these schools. It's just a state of matter and magic, nothing more. -Curator

Application-based: life and death

Life and death magic do not really warrant their own categories since they are deeply artificial and combine all three of the above categories, but because they have been so important to the medical world and the economy they were awarded with their own official school. Life and death magic explore, manipulate, and study the living body of any organism, be it plant, animal, fungus, or otherwise. Because of how this is a combined category, there is a great deal of applications and casting forms to these schools.
The medical application relies mostly on duplication. Life and death mages can map out the cells of a living tissue and based on the cells their magic explored in the past, can duplicate said cells. This happens without getting insight in how the matter they manipulate looks, so many societies are unaware of the existence of cells and see it as a duplication of flesh and tissues. This doesn't come without its dangers, as one of the largest risks of this magic is to develop cancers and other illnesses or to damage tissues so badly rot sets in. It hasn't yet dropkicked society into an age of perfect health, and a great majority of pathologies still can't be cured with this magic. The divide between life and death is vague; life mages tend to work on living patients while death mages tend to work in research on ill specimens and research them post-mortem.
The non-medical applications are endless. They can range from mind and body control to mind reading to necromancy to spreading illnesses, all of these deeply specific techniques that require many years of study and a creative mind potent in controlling their school to carry out. For this, life and death magic are controversial, requiring far more licensing to be allowed to study and practice. Some societies hold a stigma against all life and death magic regardless of its application for these unethical uses.

Magic system type

Physics-based

Key components

Natural energies

Resource

Mana energy

Eligible species

Demons, angels, some other sapient and sentient creatures

Schools

Frost
Fire
Wind
Water
Earth
Light
Darkness
Life
Death