Art of Duality

The Art of Duality (陰陽術, "Onmyōjutsu") is a special form of Magic, or rather, it is an alternative form of accessing it, akin to a Curse; more accurately to the point, the Art of Duality is deeply rooted within traditional esoteric cosmology, a mixture of natural science and darkness-based magics. As the name suggests, the Art of Duality is mainly based upon yin and yang, though it also takes some inspiration from the five element philosophy. With its complex history and myriad influences, the Art of Duality is a spiritual path that tries to find a personal balance with the world. It deals with the user's magical power being harnessed in a way that resembles divination, astrology, alchemy, and exorcism.

Description
The Art of Duality is a special form of Magic that has been lost to the sands of time and only recently been reclaimed; it was rediscovered being taught by the Takatsukasa Clan (鷹阜族, Takatsukasa Zoku) of Minstrel and it was spread across the globe both via word of mouth and many off-shoot schools. The Art of Duality is a revolutionary magic system, created by incorporating religion, cosmology, and normal magic into its basis, making use of several protocols and a theory referred to as the Reverse Soul Technique (反魂の術, Hangon no Jutsu) which involves the user manipulating their Magic Origin, allowing them to bestow certain properties upon certain divined objects an much more, making it's spells capable of many possibilities and feats such as the ability reincarnate or even resurrect the deceased. Effectively, the Art of Duality taps into the cosmic forces and the effect that they have upon the mortal plane with the user's Magic Origin with Ley Lines (, Rei Rain lit. Dragon's Vein) acting as a conduit, allowing them to use the supernatural energies which exit within the mortal and astral plane to induce the transformation of all sorts of energies; the visual representation of this is manifesting all sorts of Pentagrams (五芒星, Gobōsei). With the Art of Duality, the user can read the flow of energy and determine its course; this permanently activated state is referred to as the Perception of Evanescent Life (無常感, Mujōkan).

The techniques utilized by the users of the Art of Duality, who are referred to as Duality Masters (陰陽師, Onmyōji), are shown to have abilities which encompass a truly immeasurable amount of functions both in and out of combat- these include offensive, defensive, and supplementary techniques- elemental attacks, barriers, exorcizing spirits and demons, and divination are just a few examples. Indeed, the Art of Duality allows the user to bestow certain properties upon certain divined objects an much more, making it's spells capable of many possibilities and feats such as the ability to reincarnate or even resurrect the deceased at higher levels of usage. Despite its rather esoteric origins, the Art of Duality is solely focused on practicability while maintaining its uniqueness, rather than flashy spells that eat through the user's magical power a mile a minute, which are ever-so-common in regular Magic. The Art of Duality is more often than not frequently associated with paper seals referred to as Honourable Charms (御札, Ofuda) and chanting, though in certain cases, for exceptionally skilled Duality Masters, they can harness their abilities without the need for such wordy mantras, increasing their deadliness all the more.

In addition to all of this, a user of the Art of Duality is capable of harnessing bog-standard elemental manipulation. Traditionally, the five elements used in the Art of Duality are represented by the Five Element Philosophy, also known as the Wu Xing, with the five elements being Wood (木, ki), Metal (金, kin), Earth (土, chi), Fire (火, hi) and Water (水, mizu). The Art of Duality has a concept referred to as "cycles", where each element affects another, either positively or negatively, similarly to Rock-Paper-Scissors. Indeed, with the Art of Duality, the user is shown to be capable of harnessing the five elements with ease, creating and destroying them, altering them according to their desires as much as they want- this is the only part of the Art of Duality that doesn't require a Drive in order to bring out its full potential. Due to the Art of Duality's deep roots in cosmology, the style has the ability to deal extra damage to those of demonic and spiritual origin, including Etherious and Summon Beasts. Indeed, the Art of Duality is touted to be a "Slayer Magic except not really" in regards to those beings. Despite being rather reliant on the Honourable Charms and Ritual Gods, the Art of Duality is known to be easily one of the more powerful "forms" of magic, easily surpassing Caster Magic, Holder Magic, and perhaps even Curses; the Art of Duality is even said to be akin to a Lost Magic. Overall, the Art of Duality is such a revolutionary magic that is an institutionalized aspect of the society of Minstrel, with multiple applications in various fields such as medicine, and technology.

Mediums

 * Drive (, Doraibu lit. God Manipulating Machine): A Drive is a "medium" (仲介物, chūkaibutsu) that each Duality Master utilizes for, well, a medium for the more object-based parts of the Art of Duality. The Drive is created upon the Duality Master learning the Art of Duality, forged from their own magical energy being imbued within an item that the user holds great affinity towards; the affinity can vary depending on one's love towards the object, or simply an overall fondness for their Drive to-be. In any case, the item of choice is imbued with the user's magical energy and branded with a seal referred to as the Reverse Soul Seal (反魂の封印, Hangon no Fūin) which grants the Drive the ability to serve as a medium for which the Duality Master uses to maintain their Honourable Charms and Ritual Gods, among other things. The Drive's power manifests openings in the Demonic Portals (鬼門, Kimon), gates to the astral realm in the Cardinal Directions (基点, Kiten) which constantly leak enormous amounts of supernatural energy. In any case, when the Duality Master points their Drive either North, South, East, and West, the Drive summons a pentagram which links to the gate, instantly absorbing a certain amount of energy leaking from the Demonic Portal into the Honourable Charms which manifest according to the user's whim, allowing them to perform numerous techniques. A Drive can be categorized into three types; Attack-Type, Supplement-Type, and Clad-Type. Each form has its own strengths and weaknesses.
 * Attack-Type ( 攻撃型(アタック・タイプ), Atakku Taipu lit. Offensive Type): The Attack Type is the most common of the Drive types- they were developed as a basic model, though even though they are considered 'generic', they are easily the strongest, albeit not the most flexible. Attack-Types normally take the form of offensive-based weaponry, such as swords, guns, spears, hammers, and many more. The Attack-Type focuses solely on sheer brute force or overwhelming attack power.
 * Supplement-Type ( 応援型(サプリメント・タイプ), Sapurimento Taipu lit. Support Type): The second type, Supplement-Type is slightly rarer, though it is relatively easy to manifest. As the name indicates, the Supplement-Type has a Drive in the form of shields and other defensive armaments. The abilities exhibited by Supplement-Types are generally geared around shielding and the like- in addition, they can be used for numerous other tasks. It should be taken into consideration that in terms of special abilities, a Supplement-Type can possess such powers as augmenting energy, healing, firing elemental blasts, manipulating aspects of the mortal plane, and many more.
 * Clad-Type ( 満鎧型</rb>(</rp>クラッド・タイプ</rt>)</rp>, Kuraddo Taipu; lit. Full Armour Type): The final type, Clad-Type, is the most elusive of the Drives- as the name indicates, the Clad-Type is an evocation of an armour- the Drive forms a full body armour to encase the wielder's body in; essentially shrouding their form in power. This provides a significant increase in speed, strength, and durability, in addition to the ability to replicate a Ritual God's personalized abilities to a smaller extent. The Clad-Type, because of this, is regarded as an all-rounder between the Attack-Type and the Supplement-Type. However, the rarity of the Clad-Type stems from a general lack of truly immense willpower on the part of many wielders.
 * Honourable Charms (御札, Ofuda): The Honourable Charms are paper talismans which enable the Duality Master to perform high-level techniques. Going into a slightly more descriptive language, the Honourable Charms are always rectangles of paper with holy or magical symbols/spells written on them; these symbols are kanji, the official language of Minstrel. The Honourable Charms are the main armament of a Duality Master; fulfilling the purpose that standard "spells" would do for Magic. The Honourable Charms can be properly utilized when the Duality Master uses their Drive to manifest the Honourable Charms from their own Magic Origin, and each Honourable Charm can be charged with a certain amount of energy leaking from the Demonic Portals in each direction, and with their Drive, they manually and instantly write the kanji for the action they wish to perform upon the Honourable Charm, before mentally commanding them to do so. While the Honourable Charms have countless uses such as enhanced elemental manipulation and manifesting weaponry, they can also be utilized to create a protective ward, seal a building, dispel evil influences, or even as a weapon against those of malign intent; they have effects such as dispelling a petrifying venom, immobilizing enemies, reversing spells, make plants bloom, explosions, and send messages to other people; interestingly, the Honourable Charms have shown to be capable of binding and sealing all sorts of magics, especially those of the Slayer Magic class, as the paper talismans can reverse the effects of a Slayer's enhanced physiology against them. What is interesting about the Honourable Charms is that the moment the kanji is written upon the paper, it can instantly invoke devastating effects to both the opponents as well as the immediate environment, making the Honourable Charms much faster than most 'normal' spells.
 * Ritual Gods (式神, Shikigami): The Ritual Gods are pieces of coloured paper which are small, folded and artfully crafted manikins. Effectively, the Ritual Gods function in a similar way to familiars or more accurately, Summon Spirits such as Celestial Spirits—however, they are invisible, out of sight, out of mind for anyone sans the Duality Master a majority of the time, and by communing with the spirits that make their homes through the world, the user can bind the spirits into the coloured papers, effectively creating a Ritual God. When a spirit is bound to the coloured paper, the Ritual Gods will appear before the Duality Master and asks what the owner desires, and if it is to the Ritual God's liking, it will accept and a contract will be formed. Once the terms of the contract have been fulfilled, the Duality Master and Ritual God will part. The Ritual Gods are the partners and guards of the Duality Master, though, to put it roughly, they are servants or slaves, even 'tools'. With them, the user able to materialize these deities by projecting their spirits outside the coloured paper to perform anything that they desire upon a whim as long as it is not impossible.

Shikigami Combat
Ritual God Summon (式神召喚, Shikigami Shōkan): The Ritual Gods are pieces of coloured paper which are small, folded and artfully crafted manikins. Effectively, the Ritual God function in a similar way to familiars or more accurately, Summon Spirits such as Celestial Spirits—however, they are invisible, out of sight, out of mind for anyone sans the Duality Master a majority of the time, and by communing with the spirits that make their homes through the world, the user can bind the spirits into the coloured papers, effectively creating a Ritual God. When a spirit is bound to the coloured paper, the Ritual God will appear before the Duality Master and asks what the owner desires, and if it is to the Ritual God's liking, it will accept and a contract will be formed. Once the terms of the contract have been fulfilled, the Duality Master and Ritual God will part. The Ritual Gods are the partners and guards of the Duality Master, though, to put it roughly, they are servants or slaves, even 'tools'. With them, the user able to materialize these deities by projecting their spirits outside the coloured paper to perform anything that they desire upon a whim as long as it is not impossible. The more skilled a practitioner is, the more precision and control they can exert over their Ritual God.

A high-level practitioner can even synchronize with their familiar to the point where they can feel what they do, infusing their magical energy into the Ritual God in order to drastically increase their familiar's power. In addition, the master's magic can't harm the Ritual God. It is noted that there is twenty-four families of Ritual Gods, three per family for a total of seventy-two to represent each solar term; each Ritual God has a distinct appearance with their own special weapon(s) and a class; which are named after gods and flowers. With them, the user able to materialize these deities by projecting their spirits outside the coloured paper to perform anything that they desire upon a whim as long as it is not impossible. A Ritual God hovers around the Duality Master in a similar manner to that of a wraith; hovering behind and above the user while usually being invisible to those unaware of them; they can attack in tandem with the user, bolstering their strength significantly while working as a medium to cast higher-powered Sealing Spells.

Each Ritual God, depending on the amount of magical power used to bind the spirit into the coloured papers, is extremely powerful, and their Certain-Kill Techniques (必殺術, Hissatsuwaza) can be activated when a Duality Master syncs their Drive with the Ritual God. Depending on how much of their energy the user harnesses to manifest the Ritual God in the mortal plane, the monster attacks and then leaves, or it will stay and continue to attack until defeated or its time runs out. The strength of the Ritual God is not affected by the magical strength of their summoner unlike other summon spirits- they are all consistently powerful, with even the weakest being beyond any S-Class Magician. The magical levels of the Ritual Gods are charged by giving and taking damage in battle, or avoiding an attack. After the respective Ritual God's power is launched, the magic levels returns to the state it was in prior to the summon, meaning if the level was full before the spirit was summoned, the spirit can launch two attacks in a row. When a spirit is defeated the level is reset to zero.

Sealing Spells
Sealing Spells (封印呪, Fūinju): Sealing Spells are the, well, "spells" of the Art of Duality. The Sealing Spells are prepared by each Honourable Charm being charged with a certain amount of energy leaking from the Demonic Portals in each direction, and with their Drive, they manually and instantly write the kanji for the action they wish to perform upon the Honourable Charm, before mentally commanding them to do so; this results in an outflow of energy from the Honourable Charms, with the Duality Master invoking the Sealing Spells by using the Honourable Charms as a medium in order to induce all sorts of powers that affect the environment and the Duality Master's adversaries. The Sealing Spells have two categories, similar to the Holder Magic and Caster Magic of regular Magic; referred to as Yin Spells (陰呪, Inju) and Yang Spells (陽呪, Yōju). The Yin Spells focus more on energy-based combat and manifesting more weaponry similarly to Caster Magic and certain types of Holder Magic, whereas the Yang Spells are geared towards support and defensive-type powers such as healing, status buffing, and barriers.

It should be noted that each Sealing Spell is graded on a scale ranging from one to one hundred, with each spell becoming stronger as the numbers are increased; though, as a (slight) drawback, Sealing Spells become more difficult to properly maintain as the numbers as scale. Additionally, Yin Spells and Yang Spells do not share the same scale, as there is one spell for each number for both; though there can be multiple variants of a single spell. Normally, each Sealing Spell requires a specific Divine Incantation (天呪文, Tenjumon) and specific Nine Symbolic Cuts (九字切り, Kuji-kiri); various hand seals based around the Chinese zodiac; this generally puts Sealing Spells in a disadvantage compared to regular magic spells in regards to casting time as each Sealing Spell requires a few seconds to perform, though skilled practitioners are capable of ignoring both the Divine Incantation and Nine Symbolic Cuts in order to cast the Sealing Spell instantly. Generally, the power output of a Sealing Spell relies on the power of the user, as even a low-level spell can be utterly devastating when utilized by a skilled Duality Master.

Yin Spells

 * Yin Spells (陰呪, Inju): As mentioned above, Yin Spells focus more on energy-based combat and manifesting weaponry to assist the Duality Master in a similar manner to that of Caster Magic and Holder Magic; to put it simply, the Yin Spells are offensive spells which inflict direct damage to the enemy, harnessed through the Duality Master using the Honourable Charms to induce offense-based powers. Their effectiveness differs depending on the user; and it is said the effectiveness of the higher-ranked Yin Spells are beyond imagination.
 * Red Formula' (赤の式, Aka no Shiki): The Red Formulas govern over the Five Elemental Philosophy, having control over Wood (木, ki), Metal (金, kin), Earth (土, chi), Fire (火, hi) and Water (水, mizu); indeed, the Red Formulas revolve around elemental manipulation; which is one of the most basic and versatile forms of combat that there is- Duality Masters who use Red Formulas are extremely common, thanks to the numerous elements that they can tap into. The capabilities that Red Formulas provide are moving, altering, and mixing existing elements or pulling energies together and creating a single energy particle from many others, which is then accelerated into their element of choice. The Duality Master can generate a Red Formula from their Honourable Charms or from themselves; some users are more specialized than others, harnessing numerous properties of a single element, or going in the opposite direction as to control numerous elements at once. Certain Duality Masters are able to effectively manipulate their element with minimum bodily movement, such as by using only their head. The most common ability that Duality Masters with Red Formulas show is the ability to generate and project varying waves of elemental energy from their Honourable Charms; such energy can take the form of concentrated blasts, concussive explosions, waves of force or self-perpetuating beams. These beams can come from anywhere and be used or directed in a large numbers of ways depending on the character whether it's defensive or offensive.
 * Blue Formula (青の式, Ao no Shiki): The Blue Formulas involve the creation and summoning of powerful spiritual weaponry out of thin air to use at any time. In any case, when utilizing Blue Formulas, the Duality Master focuses the energy gathered by their Honourable Charms, intensifying it greatly before shaping the energy into the material composition and design of a weapon that immediately comes to mind; and as stated above, effectively creating a weapon out of thin air through energy alone. Depending on the user's imagination and the amount of energy used, a Blue Formula can be utilized to form almost any weaponry at all; a master is capable of conjuring anything from nothing. Functioning in a similar manner to that of a supposed alchemy, when forming a weapon with a Blue Formula, the energy channeled through the user's Honourable Charms simply manifest all the raw materials and construction methods needed for the formation of the weapons, and as long as the user can remember it, or has seen it, there is no limit to what weaponry can be manifested. Close combat weapons such as swords and spears can be created effortlessly, though due to the intricate workings of existences such as guns, they are slightly more difficult; shields and staves can be reproduced with a much greater struggle, as the cost in energy is high, two or three times greater than a bladed weapon. As they are created from energy, creating many weapons causes the user to lose a considerable amount of energy.
 * Yellow Formula (黄の式, Ki no Shiki): The Yellow Formulas all involve various other effects, such as teleportation, bodily transformation, and the like- they are simply grouped together in one category to avoid making the Art of Duality "needlessly complicated". In that way, the rest of the Yellow Formulas are similar to other offensive-based Caster and Holder Magics.
 * Black Formula (黒の式, Kuro no Shiki): The Black Formulas, also known as the Yin-Yang Spells (陰陽呪, Inyōju), are the secret "third" form of Sealing Spells, which are, well, as the name would indicate, a fusion of both Yin Spells and Yang Spells. They are often regarded to be illegal; use of such spells will commonly result in some form of lengthy imprisonment or worse within Minstrel. More often than not, the Black Formulas involve manipulating that "which cannot be bent normally", such as space and time as well as the user's very own essence; an example of this is the Large Mountain Borough Ruler Festival (泰山府君の祭, Taizan Fukun no Matsuri), which kills the user and reincarnates them in a new form. However, each Black Formulas, if it does not kill the Duality Master outright, will shave decades upon decades of their life off at a time.

Yang Spells

 * Yang Spells (陽呪, Yōju): Yang Spells are, as stated before, geared towards support and defensive-type powers such as healing, status buffing, and barriers. They are more often than not supplementary spells which can immobilize an enemy or have an effect besides a direct strike. They may seem subtle, but these spells can give their users a tactical advantage when used properly; these are a broad category of spells which all have to do with supporting the user and their allies; while mainly used as defensive measures, the Yang Spells are capable of binding, sealing, and even outright damaging magicians who use magic which alters their physiology.
 * Bounded Field (結界, Kekkai): Bounded Fields are Yang Spells which focus and project outward the energy gathered into the Honourable Charms, shaping it into a solid form of energy; the barrier formed can take upon many shapes and colours- it is determined upon the user's will. Of course, the Bounded Fields are known to be protective in nature, and can be as simple as a barrier only protecting one direction or encompassing all sides of an area; interestingly, the Bounded Fields can have numerous "properties" installed within them, such as being used to contain an enemy, or being slammed into opponents at high speeds; they can also obscure magical energies, making somebody magically and physically invisible. Of course, like all Sealing Spells, the strength of a Bounded Field is dependent upon the power of the Duality Master forming the barrier with weak barriers being capable of shattered by just about anything, while stronger ones can defend the user against the blast of an Abyss Break spell. The complexity of the shape is limited by the user's ability to imagine, as in, mentally visualize a particular form and keep it in sharp mental focus: not even the user is able to see the forms that they create. The size of a given Bounded Field projection is also limited by the user's ability to imagine. The smallest force projection they can visualize and maintain the visualization is the size of a marble, whereas the largest solid force projection they can visualize and maintain is about one hundred feet in diameter. Certain barriers can be placed beforehand and activated later, while others require certain artifacts and time to activate. Interestingly, any highly-skilled user can shape the Bounded Field into numerous seals of varying shapes and sizes which can completely immobilize a target; restrict movement, or unseal objects from any point near the target, even within them.
 * Healing Formula (治癒の式, Chiyu no Shiki): Healing Formulas are, well, spells which heal the user, their allies, or any other sort of target. Most of the time, Healing Formulas do not have known Divine Incantations and Nine Symbolic Cuts to cast, and simply heal the target; the reason why these were shelved was because even a few seconds means the difference between life and death. When performing any Healing Formula, the user holds their Honourable Charms above their patient's wounds, and a small circular glyph of energy appears underneath the targeted character, with a leaf motif in the design. As the circle is drawn, green energy flows from the glyph in order to facilitate healing. When one heals with a Healing Formula, they will attempt to restore the target's magical power firstly, as magic greatly accelerates healing of the body anyway, therefore doing half the job by itself. A Healing Formula, at its highest levels of usage, can completely restore a target's magical energy and stamina and cure them of any status ailments before finally granting them a stat boost.
 * Divination Formula (予見の式, Yokan no Shiki): The Divination Formula is one of the basic "techniques" of the Art of Duality; it is a "future sight" which grants the Duality Master a 'third eye' of sorts; their Drive, due to channeling the output of energy from the Demonic Portals, the Duality Master is capable of seeing the flow of energy throughout the world, granting them an excellent sense of precognition, recognizing the patterns of the two planes, enabling the prediction of natural disasters and astrological events; this also warns the Duality Master of potential immediate danger, enabling the Duality Master to evade most any injuries, unless the user cognitively overrides their automatic reflexes; however, for every choice the user makes when following the Divination Formula, another path is shut off from their access as to prevent a sensory overload- meaning that the "chosen" path could have been wrong all along. The Divination Formula can create a general response on the order of several minutes, guiding the Duality Master away from hidden weapons and enemies, and with it, the user can casually dodge attacks up to and including automatic-weapons fire, provided there is sufficient distance; a skilled user can manipulate the exact probability of an incoming attack or event, effectively granting them a minor form of reality warping.
 * Reinforcement Formula (増強の式, Zōkyō no Shiki): The Reinforcement Formulas serve as 'status buffs'; when initiating a Reinforcement Formula, the Duality Master focuses upon their targets and expands Honourable Charms towards them, temporarily surrounding the targets, which can be multiple, with quavering auras of energy, granting them enhanced attack power and speed. In addition, it also boosts their defensive power. It grants a tremendous boost in power all around the board; the targets receive an enormous augmentation; enough to buff them up to at least SS-Class level mages, who are capable of throwing down with the best of them; aside from bolstering their speed, increases the chances of landing a critical hit. It also enhances their offensive power for a certain period of time. It triples the next physical attack's strength. Multi-hit attacks only increase the power of the first strike. If an attack is physical but relies on a set factor, it still increases in power; increasing their physical and magical defenses by halving all damage done to them, including offensive and curative spells, as well as physical attacks, including attacks unleashed armed, and those unarmed. The effect can stack; and anything that was good is made great.

Trivia

 * The Art of Duality was based upon, most obviously, Onmyōjutsu, which is a real thing- though the Fairy Tail iteration takes inspiration from other sources of Onmyōjutsu, such as Tokyo Ravens, Onmyō Taisenki, Shaman King, and numerous others.