The system of Arcana was brought about as a result of the very first Conformity to occur upon Irithria, emerging as a result of the Ormr's belief that they were meant to be the star's custodians. At that time, they knew it as the Blessing of Creation, and it would be known by this name for much of the world's history, only starting to be referred to as Arcana during the time of the Grannrormrlen. It remained the sole Conformity-made system of techniques to be utilised on the continent for multiple millennia prior to the creation of Theos by the Leskeln, at which point its usage began to dwindle in favour of the newer, far more easily utilised, and arguably more powerful system.
Capabilities
Arcana was created with the fulfillment of the Ormr's desire to terraform the star in mind. For this reason, it excels at the creation of both matter, and new life. Arcana was used by the Ormr to raise great mountain ranges, bring into existence swathes of plantlife where there was only dust, and create entirely new forms of life such as the Leskeln. The key principle of Arcana is that if something can be visualised in the mind's eye, it can be created. For this reason, Arcana's capabilities are extremely wide-ranging, and it has been used for innumerable projects both great and small over the years.
However, the system does possess a number of fundamental limitations. Firstly, it is impossible to use Arcana to remove or directly destroy something that already exists. This function of the system is representative of a unique quirk of the Ormr's psyche; namely that they found it tremendously difficult to imagine physical objects that they could see not being where they were. As well, it may also be to do with the fact that Arcana was designed to create, not destroy. It is still possible through certain creative applications of the technique to achieve the desired effect of destroying or otherwise removing matter, however. This has often been achieved throughout history by fabricating explosions at a desired location, which would then damage whatever was around them.
The second limitation is that of visualisation. The majority of the time, it is only possible for an arcanum to affect an area that is within the invoker's line of sight. This is not a hard limit in the way that the inability to remove matter is, and rather comes about as a result of the inherent difficulty in visualising something that one cannot see. Arcanums will fail if the visualisation of an area is not almost perfectly in line with the reality of that location, meaning that even a minor misremembering of a place that is out of sight will cause one to fail. This imposes a restriction upon the area in which arcanums can be cast to that which the invoker can readily visualise, which in the case of the Ormr was several square kilometres at a time, and in the case of humans usually just a few metres at most. Additionally, objects or materials with uneven surfaces or certain other qualities - such as transparency or reflectivity - may make them extremely difficult to accurately visualise. Examples of such materials include glass, water, and bismuth; which is why the latter is used as currency throughout mainland Pretheya.
The third limit pertains to the emotional requirement to complete an arcanum. Each manifestation made via arcanum necessitates the expenditure of a requisite amount of emotion, which serves as the catalyst for the invocation's completion. The emotion must be of the correct type pertaining to the material being manifested, determined by the associations which the caster holds with that which they are fabricating. This means that on one hand, it is tremendously difficult to create something which one has very few feelings about. On the other hand, depending on the nature of the emotion, it can be very hard to conjure up the correct feeling to be used as fuel for an invocation. This is particularly true of arcanums that would require delicate or specific emotions to invoke, such as affection. The inverse also applies, with arcanums that require easily accessible types of emotion - such as those which use anger or the urge to commit violence as catalysts - often being relatively simple to perform.
Due to the stringent requirements to do with visualisation, it is necessary that a degree of interpolation be performed on behalf of the mechanism, or else no arcanums would be capable of being invoked. This refers specifically to the interior of created materials, which was impossible even for the Ormr to imagine. Because of this, if it had been necessary for them to visualise the insides of an object, they would never have been able to fabricate anything, and so the technique waives the requirement for a user to do so in exchange for automatically filling in the interior of created materials based on the user's intent and expectations. The same is true of lifeforms created through Arcana: The Ormr had no idea about the existence of internal organs when they created the Fyrstbairn, and so in order to fulfill their goal of 'having them be alive', it was necessary for the system to step in and fill in the blanks in the Ormr's specifications.
Utilisation
Individual usages of Arcana are referred to by practitioners (a single one of which is themselves called an esoterikos, with multiple being referred to as esoterikii) as arcanums. There are two key components necessary to completing an arcanum; the visual component and the emotional component.
Visual Component
The first component of weaving an arcanum is successful visualisation. An esoterikos achieves this by first picturing the world around them, specifically the portion of it which they wish either to enact an effect upon or fabricate new material within, in as much detail as possible. The requirements for this to be successful are extremely strict: In order for the visual portion of an arcanum not to fail, the esoterikos must be able to visualise the geography and appearance of the real world location where they wish to perform the invocation at a level of detail comparable to how they would be able to see it were they physically looking at it. Not only this, but their visualisation must also be accurate to the real physical location; ie, if they were to accurately visualise a box that was not really there, the arcanum would fail.
Once they have succeeded in visualising the location and environment in which they wish to perform the arcanum, they must then visualise what they wish to invoke by means of it in the same level of detail. For example: If an esoterikos wished to fabricate a cube of granite, once they had successfully envisioned the environment, they would then need to imagine a cube of granite imposed within that environment. The imposed object must be visualised with a level of clarity as if it were actually there, down to the details on its surface and the shadow it casts within the light. This process must be repeated for every major angle that the object can be viewed from, without allowing any of them to fully slip from their mind, lest they have to begin again. Assuming they succeed in doing so, the visual component of the arcanum is now complete.
Emotional Component
Arcanums also require an emotional component in order to be invoked. The emotions required for the invocation of an arcanum depend on what emotional associations the esoterikos has with the subject that is their desired result, and must be of broadly the same type. For example: One of the most common arcanums taught to esoterikii intending to serve within the military is how to manifest a plume of explosive force. In this case, given that the arcanum is likely being used to hurt or kill another person, and involves creating what will shortly thereafter become a large ball of fire, an esoterikos would likely associate this arcanum with feelings of anger, hatred, violence, and the desire to kill. These, then, are the feelings that they must embody in order to successfully complete the emotional component of the arcanum.
When an esoterikos begins an arcanum, the emotions they are currently experiencing will be used as fuel to complete the invocation, and will vanish from their psyche the moment it is complete. Depending on the scale of the arcanum wrought, this may range from a mild sensation of dullness if only a part of their emotions were drained, or may manifest as a feeling of complete emptiness and the absence of any feelings whatsoever in more extreme cases. In the event that an esoterikos finds that their emotions have been completely drained by an arcanum, they must work back up the necessary emotions in order to perform another arcanum. This generally becomes more difficult with each arcanum completed in quick succession, and after two or three, an esoterikos may become exhausted to the point of being rendered temporarily unable to feel.
This naturally provides a severely limiting factor in the usage of Arcana, far more so than the visual requirement to complete an arcanum. Esoterikii engaged in warfare must take great care to make sure that their emotions do not wander from what they need in order to perform their desired arcanums, and they often will have to limit themselves to only invocations that rely upon one specific emotion, which can limit the range of arcanums that they can call upon significantly. More skilled esoterikii may be able to hold two to three emotions in tandem, such as most commonly fear and anger in the context of a battle; the former being particularly useful to expend as it allows them to remain uncowed in the face of battle.
The stress of combat can lead to greatly heightened states of emotion, allowing an esoterikos to call upon more arcanums before they are depleted of feeling. This comes with a significant downside, however: Most esoterikii who end up pushing themselves beyond their normal limits in battle are left exhausted for multiple weeks, potentially even months, afterwards, during which time they cannot invoke any arcanums whatsoever and may even need to be taken care of by other people. The psychological toll this takes is also immense, and frequently leads to the development of maladaptive coping mechanisms and other disorders within esoterikii; in some cases even causing them to burn out completely and lose the ability to wield Arcana.
Outside of combat situations, the safe utilisation of Arcana is far easier. The majority of esoterikii will limit themselves to only performing one or two minor arcanums a day, and in this way will refrain from overtaxing themselves; leaving them fresh enough to do the same the next day. Esoterikii working on long projects, such as decorating buildings or fabricating works of art, may instead choose to work in long bursts followed by extensive periods of rest afterwards. Esoterikii are often viewed as eccentric, and there is not considered to be any one 'proper' way of working as one; as such, matters like these are largely left up to personal preference.
Usage Throughout History
Pre-Law of Mortality
The Blessing of Creation was used by the Ormr to spread life all across Pretheya's surface in the form of trees, plants, and eventually animals; the first of these being the Fyrstbairn and the Leskeln. Together, the Wyrms went as far as to terraform the very geography of the world, raising mountains where there had been none so far and even flattening entire areas of land in order to use them as gardens. The Ormr's greatest achievement with Arcana was the enactment of the Law of Mortality; a universal natural law which caused all life upon its surface to become capable of death.
The Vikingar
After the Law of Mortality was enacted, the Ormr utilised Arcana to begin mending the damage inflicted by the Deluge. It was here that for the first time, the Wyrms had to concern themselves with utilising the Blessing of Creation not just for their own pleasure, but also for their survival, which lead to them creating various installations designed to produce food or funnel water down pathways of their choosing. To this end, they created numerous great holds for both the Fyrstbairn and the Leskeln, also expanding the forest of Ethlarnashem to the size of a small country in order to provide the latter with a place to live after they were nearly wiped out by the flooding. The majority of the unusual flora and fauna that still exist on Pretheya today were created during this time, such as the rainbow glade in Vaeoule, Belyria's gemstone forests, and the Cloudboughs of Sassania.
During the Grannrormrlen
The only large-scale usages of Arcana after the first phase of the War for Heaven were performed by Forfir or his Fyrstbairn governors. The most notable of these was Forfir's project to raise the Silver Mountains around Landamar, in order to be used as defensive terrain to protect against potential Leskeln incursions. Attempts were also made to rejuvenate the wastes of former Arcadia, but were unsuccessful due to Arcana being unable to affect the land there. It was also at this time that humans first learned how to use Arcana, and began wielding it in a military capacity against the Leskeln. Over the next centuries however, they would come to utilise it in the same fashion as the Wyrms, albeit in a far less adept manner and on a much smaller scale.
Advent of Theos
The creation of the Blazing Empire and the introduction of Theos to Pretheya saw Arcana's usage steadily begin to decline throughout Pretheya as it was eclipsed by the newer Conformity system, which required far less training to use and was arguably more powerful. By the time of the Empire of Karvinasstrad's collapse, Arcana had all but ceased to exist within Shahru lands. It continues to be practised all the way up to the present day within Asatro countries, such as the Granrik of Heralya and the Kingdom of Sassania, where it plays a core part within the two nations' militaries.
Present Day
In the current Age of Divinities, Arcana has largely fallen to the wayside within countries that have embraced the Rukhmarite faith. For those willing to submit themselves to the authority of a deity, there is little that Arcana can accomplish that cannot also be achieved through Theos without any need for the extensive training required to produce an esoterikos.
The people of some countries, however, refuse to become slaves to a god, and so reject Theos and continue to rely upon Arcana. This is primarily the case within the Landamaeri kingdoms that still follow the old Ormr tradition, seeing the followers of Shahru as heathens who worship a being considered in part responsible for the downfall of the Grannrormrlen.
Military Usage
The vast majority of military esoterikii are trained in the use of a number of elementary arcanums, usually a variant of the Basic Combat Arcanums first invented by the Granrik of Heralya. These are invocations with simple visual and emotional components designed to be able to be utilised by any esoterikos, regardless of the idiosyncracies of their Arcana, which can then be easily accounted for in tactical planning. Owing to the immense resource investment it takes to train an esoterikos up to a professional standard, present day doctrine involving the usage of esoterikii frequently limits them to support roles, in order to minimize the risk of injury or overtaxation. Despite this, they are still trained and equipped to be able to be deployed on near-front-lines combat if the situation should require it.
Basic Combat Arcanums
Every esoterikos in the Heralyan army is expected to be capable of performing the following arcanums: The precise materialisation and invocation of a lightning strike, the fabrication of a ball of explosive force, and the prompt creation of a gust of wind with which to repel arrows. The purpose of teaching all esoterikii these arcanums is in order to standardize their use as a tactical asset: If a commander knows that each of his esoterikii will at the very least be capable of performing these basic arcanums, then he can dispatch any one of them to perform one of these tasks without needing to pause to consider their individual capabilities.
Support Capabilities
Depending on their individual skills, a military esoterikos may be capable of weaving any number of highly useful arcanums; with effects ranging from improving logistics to controlling the battlefield. Esoterikii with an affinity for soil can use arcanums to directly reshape the battlefield, smoothing out uneven ground, creating hills or slopes for allied troops to garrison on top of, and erecting lines of cover to protect from enemy projectiles. Others, primarily those with a background in either the culinary arts or as some variety of farmer, may be capable of supplementing an army's food supplies by the fabrication of bread or other foodstuffs. All naval esoterikii are expected to eventually become able to fabricate water, which can be used both for drinking and - if they are capable of manifesting it in large enough amounts - to control and manipulate the battlefield.
More experienced esoterikii may be capable of erecting rudimentary fortifications, such as wooden palisades or stone walls on the fly. In addition, those with constructive capabilities can be of vital importance to army logistics in preventing disruptions caused by difficult terrain. If an enemy force burns a bridge to stop an army from crossing a river, an esoterikos can simply create a new crossing point for the army. Alternatively, if it must march over difficult terrain such as a swamp, the esoterikos may be able to freeze the water to allow for easier passage.
Command Challenges
One of the greatest difficulties in leading armies with esoterikii in them is the burden it places upon commanders to memorise the individual capabilities of each esoterikos. Beyond the Basic Combat Arcanums, the majority of military esoterikii can command a completely different arsenal of arcanums, with it being not uncommon for two esoterikii to have absolutely no invocations in common other than the basics.
Other Training
In addition to their training as esoterikii and any potential other trades they may have experience in, all military esoterikii receive at least basic training with close combat weapons: Spears, swords, daggers, and in some cases hammers, halberds, or pikes. This is to ensure that an esoterikos caught in close combat is not entirely defenceless, though the majority remain significantly less skilled in melee combat than knights, who spend their entire lives training rigorously for front-lines battle. Generally speaking, the majority of esoterikii simply do not have the time available to dedicate to mastery of a weapon in addition to what they already have to learn as an esoterikos, and the second discipline that a significant portion of them are educated in. Exceptions do exist however, and some esoterikii who have been groomed for a career in the military function essentially as arcanum-capable knights.