Shade Manifestation

Shades (also known as Ghosts or Glitches) is the collective term given to the occult and rare meta-dimensional manifestations that are known to occur around areas of high arcanic concentration.
Despite having been witnessed by almost all space-faring species and civilizations, and even having been a key part of Boshaari pre-industrial life (where they were loosely associated with Fallanist beliefs in entities called Æsimar and Erinyæs), very little is understood about these manifestations. Some seem almost gifted with wilful intentions, whereas others are little more than glitches in the fabric of reality.
Shades are of particular interest to followers of the Aeonic Way, who summon and analyze them for evidence of their demi-gods.

Classification

Shades are classified based on their arcanic attunement, general level of energy and agency, and ‘theme’.

Lesser Shades

Lesser Shades (LS) are the best understood. They are weak manifestations of arcane energy. Most often they coalesce naturally around the energy of a planet's leylines or, in deep space, around Thaumium-rich asteroids. Lesser Shades are the result of an arcane ripple or microrift between Realspace and Hyperspace - such as what might happen in areas of high arcanic interference.
Lesser Shades are generally shapeless and generally bear semblance to a classical element; thus, in common speech, such manifestations are often called ‘elementals’. They do not ‘wander’ far from their point of origin and are susceptible to dissipate should the rift be mended or altered. Fire, air, water, void and earthen lesser shades have been documented, and the Boshaari used to base their faith around such manifestations.
Several arcanists argue that lesser shades are distinct from the other categories, as they are naturally occurring and lack any sense of sentience and ‘life’.

Greater Shades

Greater Shades (GS) are not as well understood as their lesser counterparts. They are certainly constructs of arcanic energy, but they do not seem linked to particular rifts or ripples through hyperspace. Greater Shades seem gifted with rudimentary intelligence - a popular model describes these manifestions to exist as ‘concepts’ imbued with ‘principles’ upon which they act and around which they evolve.
There is certainly a high variety of Greater Shades, even with a very limited number of sightings. The majority encountered so far often align around certain themes and properties. Colloquially, they have been sorted into ‘celestial’, ‘demonic’, ‘devilish’, ‘seelie’, ‘unseelie’ or ‘unknown’ subtypes, based on their observed concepts, principles and general appearance.
Physically speaking, a Shade's 'body' can bear some similarity to mundane tissue - a powerful few were documented to effectively be organic and subject to needs beyond that for thaumic energy, whilst others seem to be content existing with impossible organs or even as conceptual shapes.
It is to be noted that such bodies are facades that only truly exist and operate due to the constant thaumic flow they feed upon. A few powerful Shades can potentially gain such dimensional integrity that it takes special weapons to dismiss them - though these very rarely occur in the generally arcane-deaf space around Tau Elpis. Most Shades are easily disrupted through the application of physical violence or hostile magical flow (or, barring that, depriving them of thaumic sustanance).

Familiars

Familiars (FS) summoned through a heavily specialized arcanist’s actions and spellweaving belong under the Greater Shade umbrella as they do not require an arcane rift to form and they possess some ability for intelligence, despite their fickle forms. A familiar which somehow escaped the guidance of its summoner is refered to as a Rogue Familiar (RFS) or sometimes as a "free-shade".

The Oberon Incursion

Many hold that the fearsome Oberon, whose existence came at the cost of that of most other sentient, living things in the Pyxis Globula and whose invasion directly led to the Great Jump, might be extreme examples of Greater Shades - vaguely faerie-like in appearance, but with the hunger and destruction appetite of more fiendish Shades, and a resilience to most attacks by conventional weaponry unseen in any other type. Generally, the Oberon have been classified as ‘unseelie’ Shades (GS-U) by the Boshaari and other species. However, any evidence pointing that way is scarce, and thus the scientific community at large has been loathe to classify the Oberon as shades of any kind. Nevertheless, because of their assumed resemblance, research into shade manifestations has become a topic of concern to researchers.

Summoning Shades

It is accepted that Greater Shades generally exist as 'concepts' imbued with 'principles' - a careful Magister will imprint such concepts as 'obey your summoner' into their spellcasting. One could see such principles as 'compulsions' that the Shade will act upon, even though most of the time, such wants and desires seem to limit themselves to 'survive'. These are very vague analogies at best, for Shades are not easily dissected or tested upon and their very existence is very alien to mundane realspace lifeforms. A few Pacters have compared shades to unbraked AI, for they will generally concern themselves with their primary 'principles' and generally show an unability to discern context or preoccupy themselves with realspace ethics and morality codes.

Shade Manifestation

The summoning of a Familar Shade is an extremely difficult act of arcane performance, far out of the reach of most Arcanists. Trained Magisters, who have devoted their entire lives to such an art, use formulae to create arcane "molds" which are intended to be filled by Shades bound to the summoner's will - though this does not always work, and more than a few Shades have emerged unbound from a summoner's Sanctum. A flawed formula can be corrected through further research, though this endeavour never has any certainty of success. Over time, a few standardized spells have emerged that can reliably summon smaller, more docile Shades - though these are often tied to the summoner's arcane energies - more akin to arcane illusions that dissipate quickly without focus.
A practitioner of Shade summoning is a Magister more generally called a Pacter - so named because many Shades tend to demand or require something in exchange for their service. This can be Thaumium, favours, or in the case of arcanist Eire Llir's voidhare servant, sugary treats. Pacters are often feared and reviled throughout most societies, and such mages are hardly encountered, partly because of the galaxy-ending impact of the Oberon attack, but also because Familiars are fickle entities which can behave dangerously under the guidance of a struggling arcanist.
It is to be noted that summoner-priests of the Chantry of the Void needn't be actual magisters and summoners, though it is highly likely that at some point in Boshaari history, many were.

Sustaining a Shade

Ritually invoked Shades generally rely on their own flow of sustaining thaumic energy, catalyzed by components used in the summoning rite. Such Shades persist indefinitely, assuming the summoner does not dismiss them or their energy matrix is not disrupted by damage or hostile spellweaving. However, if a caster loses control of a Shade because of a faulty evocation spell, they will find themselves unable to dismiss them voluntarily.
Whatever their origin, Rogue Familiars survive on limited amounts of energy more readily found in areas of concentrated thaumic flow : a sacred glade or beautiful lake on Aistanar, the backalleys of Embassy Ark's Thaumium stores or the space around Outpost X-5 and Electra Station are all typical locations where Shades precipitate and survive, though never as more than harmless elementals or natural oddities. It is a different matter on the world Zindra, where even powerful and sometimes malevolent Shades thrive due to Zindra's extremely powerful arcanosphere - whose only known counterpart was that of the old Boshaari crownworld, which was equally teeming with Shades and shaped Boshaari beliefs to this very day. A Shade which lacks fuel will begin to fade over the course of weeks and eventually dissipate - banished back to the shapeless miasma of hyperspace. Fallanists keep shrines in areas of larger thaumic flow across Aistanar to keep them sustained, as their Chantry has done for countless millenia before the Great Jump.
Stories abound about Rogue Familiars seeking cultists to enslave for sustenance or living out of cursed magitek in the manner of proverbial genies, however no instance of either has truly been ever found true, and they are almost likely the product of extranet disinfo and badly-filed horror holoflicks.

Cultural Impact

As fascinating as Shades have been to spacefaring or arcanic cultures for millenia, difficulties in shaping, controlling or dismissing them have made them unattractive to most spellcasters, with relatively few uses to the vast majority of civilizations. In the Pyxis Globula, to all but the Boshaari, they were simply arcane anomalies - at best, very convincing illusions on quarantined worlds.
Nowadays, by far the most Shade-friendly civilization is that of the Boshaari, whose ancient crownworld was extremely high in arcane energies and where Shade precipitation and summoning was seen as normal. To this day, the Chantry continues to worship Shades - though it arbitrarily splits them into three groups : benevolent Æsimar, malevolent Erinyæs and summoned Familiars). To the Mewei and Hiderid, who see the Shades as different from the Oberon who destroyed their galaxy, they are still mere oddities of arcane energy - purely arbitrary manifestations of arcane without much more meaning to them. The Hhrot see Shades as anathema to the existence of life itself - splinters of Oberon destroyers - and will go to great lengths to dispel any Shades they can find. This puts them at odds with the Boshaari, and perhaps explains the particular form of Hhrot isolationism.
There are a few groups who believe that Shades are the manifestation of a divine presence. Certainly a few devout New Fallanists at least imply that their key figure, the Inheritor, sits somewhere between very powerful Summoner and divine root of all Shade manifestation. Boshaari sometimes use the terms Æsimar and Erinyæs to describe a variety of Lesser and Greater Shades, though it is important to separate the religion from the science : many Æsimar are the stuff of folklore, with no regard to the true properties of a matching Shade manifestation, if any.