All humans, Ispoliyad, and Ispolin are born with an innate link to one of the eight planes of matter, and their biological aura resonated with that particular plane: Life (Astral), Water, Cold, Air, Death (Umbral), Lightning (Plasma), Heat, and Earth.
In ancient times, all that was known about this ability was that humans could be induced through meditation or drugs to project their consciousness into the plane they linked with. Sometimes, a human with a link to the Life plane could draw forth pure life energy to aid in healing as well.
When the Ispolin arrived, they taught humans how to cast forth their auras into runes, symbols, and songs, to actually control matter in the Plane of Transience (where humans reside) that matched their linking plane. So, for example, a human who linked with the Plane of Cold could freeze his surroundings with his aura, while a human who linked with the Plane of Heat could create fire with her aura. The High Ones also taught humans that they could summon beings from their linking plane; though this was a physically and mentally perilous endeavor, and must only be done in times of desperation.
In Arvos, casters (called shamans) learned to draw complex runes with their aural energy that detailed the effect they wished to produce. In Diskara, casters (called sages) directed their auras with complex hymns, usually in a group effort that results in time-consuming but powerful effects. In Taiya, casters (called shifu) cover their bodies with tattoos of the aural effects that they know in their own ancient script, giving them an extreme advantage in casting speed.
In ancient times, all that was known about this ability was that humans could be induced through meditation or drugs to project their consciousness into the plane they linked with. Sometimes, a human with a link to the Life plane could draw forth pure life energy to aid in healing as well.
When the Ispolin arrived, they taught humans how to cast forth their auras into runes, symbols, and songs, to actually control matter in the Plane of Transience (where humans reside) that matched their linking plane. So, for example, a human who linked with the Plane of Cold could freeze his surroundings with his aura, while a human who linked with the Plane of Heat could create fire with her aura. The High Ones also taught humans that they could summon beings from their linking plane; though this was a physically and mentally perilous endeavor, and must only be done in times of desperation.
In Arvos, casters (called shamans) learned to draw complex runes with their aural energy that detailed the effect they wished to produce. In Diskara, casters (called sages) directed their auras with complex hymns, usually in a group effort that results in time-consuming but powerful effects. In Taiya, casters (called shifu) cover their bodies with tattoos of the aural effects that they know in their own ancient script, giving them an extreme advantage in casting speed.
DOMAINS
Along with the Universal Domain of Mind- which involves a shaman temporarily controlling the aura, and thus the consciousness, and sometimes even thought, of another person- there are nine domains in total.
The domain which a person was most closely linked to is called their Primary Domain. Normally, a person would have the strongest link to their Primary Domain, and would have a lesser but still effective connection to the two domains adjacent to their Primary, called their Secondary Domains. Occasionally a human would be equally linked between Primary and Secondary Domains. Only in extremely rare circumstances would someone link with a Tertiary Domain, the two additional domains next to their Secondary Domains. Individuals with Tertiary Domains are invariably descendants of the High Ones.
Not all domains are seen as equal in the eyes of society, however. Due to the high everyday utility of Water, Life, and Earth domains, they are by far the most sought after and most well-understood domains. The heat domain is seen as rather destructive, but useful in colder regions, just as the Cold domain is seen as useful in warmer regions; and both Heat and Cold domains are fairly well understood due to their frequent presentation as Secondary Domains for Earth Primary and Water Primary casters. Air domain casters are sometimes viewed with caution due to the domain's proximity to the dreaded Death domain, but overall the Air domain itself is seen as slightly useless but neutral.
The Lightning and Death domains, however, are often outright shunned from shamanic orders. The Lightning domain is seen as too chaotic and destructive to be compatible with civilized society. The Death domain, on the other hand, is seen as plainly evil, and shamanic apprentices who are discovered to possess this domain are frequently expelled. For these reasons, the Lighting and Death domains remain poorly understood, and many Air Primary and Heat Primary casters never fully develop their Secondary Domains out of a combination of fear and lack of resources.

Arvosan shamanism domain chart, and common effects employed in each domain.
TRAINING
Though all humans have a planar link, it is important to note that most only have a weak connection. The ability to draw forth aural energy at all must be trained, and even then many do not have the talent to draw forth enough to create any tangible effects. Only 1 in 100 people can even be taught to draw aural energy properly. Adding on the fact that, to create any effect with aural energy, one must have access to a master to learn the correct runes, signs, or hymns from; and then must also have the mind to learn the mathematical calculations involved in casting- an exceedingly small amount of humans (1 in 10,000) become competent casters.
This means that even with great talent, no human can become a caster through sheer luck. All casters must go through an apprenticeship that involves years of training, and on every continent casters are organized into formal orders that serve offices and families of power.
Though all humans have a planar link, it is important to note that most only have a weak connection. The ability to draw forth aural energy at all must be trained, and even then many do not have the talent to draw forth enough to create any tangible effects. Only 1 in 100 people can even be taught to draw aural energy properly. Adding on the fact that, to create any effect with aural energy, one must have access to a master to learn the correct runes, signs, or hymns from; and then must also have the mind to learn the mathematical calculations involved in casting- an exceedingly small amount of humans (1 in 10,000) become competent casters.
This means that even with great talent, no human can become a caster through sheer luck. All casters must go through an apprenticeship that involves years of training, and on every continent casters are organized into formal orders that serve offices and families of power.
LIMITATIONS
Though there is technically no limit to how much a person can cast aural energy every day, the process is mentally and physically exhausting. Even experienced casters may collapse if forced to cast for hours on end.
Another unfortunate reality of using a shaman, sage, or shifus' skills is the potential for succumbing to insanity if a caster spends too much time connected to a foreign plane. All trained casters have a heightened connection to their linked plane, and can detect the energies of the beings and lands around them which relate to that plane. But prolonged mental projection into another plane may sever the individual’s connection to the Plane of Transience, and whittle them down into a blank-faced husk who wanders about with little memory of the person they once were.
Though there is technically no limit to how much a person can cast aural energy every day, the process is mentally and physically exhausting. Even experienced casters may collapse if forced to cast for hours on end.
Another unfortunate reality of using a shaman, sage, or shifus' skills is the potential for succumbing to insanity if a caster spends too much time connected to a foreign plane. All trained casters have a heightened connection to their linked plane, and can detect the energies of the beings and lands around them which relate to that plane. But prolonged mental projection into another plane may sever the individual’s connection to the Plane of Transience, and whittle them down into a blank-faced husk who wanders about with little memory of the person they once were.
KNACKS
Another weakness of casting, especially in the face of imminent danger, is that runes and hymns take time to implement, since every parameter of a caster’s desired effect must be mathematically calculated. Even the most skilled casters may need half a minute to manifest a proper rune or hymn. However, some casters may mitigate this handicap by intensely training one hymn or rune so thoroughly that its specific construction becomes instinct, allowing them to only cast a quick shorthanded note or rune to achieve the practiced effect. This shorthand is called a “Knack”.
Especially Taiyan shifu have honed this skill, as all the tattoos on their bodies are essentially Knacks. Due to this expediency, casting in Taiya is often intertwined with martial arts.
Every Knack is unique to its creator, is unusable by any other caster, and only creates one specific effect.
Another weakness of casting, especially in the face of imminent danger, is that runes and hymns take time to implement, since every parameter of a caster’s desired effect must be mathematically calculated. Even the most skilled casters may need half a minute to manifest a proper rune or hymn. However, some casters may mitigate this handicap by intensely training one hymn or rune so thoroughly that its specific construction becomes instinct, allowing them to only cast a quick shorthanded note or rune to achieve the practiced effect. This shorthand is called a “Knack”.
Especially Taiyan shifu have honed this skill, as all the tattoos on their bodies are essentially Knacks. Due to this expediency, casting in Taiya is often intertwined with martial arts.
Every Knack is unique to its creator, is unusable by any other caster, and only creates one specific effect.
THE SCHOOLS OF CASTING
SHAMANS
On Arvos, casters discovered that they could draw geometric runes with astral energy from their fingertips, while focusing on the mathematical equation of the effect they desired in their head; then cast forth these runes to manipulate the world. Arvosan casters are called “Shamans”.
On Arvos, casters discovered that they could draw geometric runes with astral energy from their fingertips, while focusing on the mathematical equation of the effect they desired in their head; then cast forth these runes to manipulate the world. Arvosan casters are called “Shamans”.
SAGES
On Diskara, casters took an entirely different approach, and used the vibrations of their voice to deliver their calculations through hymn. Diskaran casters are called “Sages”.
On Diskara, casters took an entirely different approach, and used the vibrations of their voice to deliver their calculations through hymn. Diskaran casters are called “Sages”.
SHIFU
On Taiya, casters developed a similar method for drawing astral energy into written glyphs; but they train to develop every glyph they learn into a Knack, so it may be tattooed onto their body and cast instantaneously.. Taiyan casters are called “Shifus”.
On Taiya, casters developed a similar method for drawing astral energy into written glyphs; but they train to develop every glyph they learn into a Knack, so it may be tattooed onto their body and cast instantaneously.. Taiyan casters are called “Shifus”.