Aether is the foundational, fundamental energy of the universe. It is the substance from which all energy and matter in I&A is derived, and it is the means by which more energy and matter may be created, destroyed, or transferred. It is an omnipresent facet of reality, present in all things, persons, and powers. It is not every thing, but it is every thing's source, and a vital component in the mechanics of the universe behaving in the ways that they do.
Typically, Aether is present as a sort of energy that passively exists in the background, on a level that is unnoticeable and imperceptible to casual observers and those blind or exceptionally ignorant to the arcane; at this level, only a being that is exceptionally mystically-inclined would even be aware of the presence of Aether. However, the more concentrated Aether becomes, the easier it is to notice, sometimes as a haze or fog of pure arcane energy, sometimes as a smell or strange feeling (perceptible via an Arcana or Perception check), but often times, Aether that has become exceptionally concentrated in one specific place and time crystalizes (or even more rarely, liquefies) into a substance known as Aetherite.
Aether made solid or, in rare instances, liquid. Aetherite is a substance that contains pure arcane power, the uses of which are many and varied. When solid, Aetherite is crystalline and surprisingly light, with 1 pound of it being roughly the size of an adult Human fist; when liquid, it is cool and clear with a water-like consistency. Generally, Aetherite is used for alchemical purposes, in the brewing of concoctions and the enchanting of items, each of which is discussed in greater detail here. Other purposes include being used in jewelry, facilitating trade, and the creation of Elemancers, who, unlike Arcanists, have implicit arcane powers that grant them control over one of the six elements.
Aetherite comes in 7 varieties: Neutral, Dark, Light, Magical, Soul, Space, and Time. The most common by far is Neutral, which is white with a gentle glow and buzzes ever-so-slightly to the touch, but does not actually physically vibrate. Neutral Aetherite is serviceable for the majority of alchemical and arcane pursuits since its raw, un-aligned arcane power is enough to give concoctions and enchants the desired enhancement. For more specialized or especially powerful alchemy, however, Aetherite of the appropriate type must be used, such as Light Aetherite being used in flame-based enchantments and Magic Aetherite being used in illusion-based ones. The exact natures and properties of each of the 6 elements are expanded on further below, and the mechanics of alchemy are explained here.
When it comes to finding Aetherite, it is primarily found in 3 locations: Aether springs, the crust of the planet, and in the aftermath of Aether storms: Aether springs are areas where naturally-formed fonts of liquid or growths of crystal Aetherite spring up out of the ground, seemingly at random and without source or cause besides the fact that the presence of Aether there is unusually strong for one reason or another; in the planet's crust, there are sporadically-located veins of Aetherite that can be mined in much the same way metals and precious gems are; and finally, when an Aether storm ravages a given area, in its wake it often leaves chunks of crystal Aetherite and/or puddles of liquid Aetherite throughout the area in which it rampaged. Though most of these sources would at first appear finite in nature, it is not unknown for sources of Aetherite to - either spontaneously or over time - replenish themselves, or for new sources to appear where there previously were none. Though Neutral Aetherite is by far the most common type found on the Central Plane, each element's plane almost exclusively has Aetherite of that element. Aether storms are covered in detail further down.
As for buying Aetherite, use 50 Aeons/pound as a base for Neutral Aether and 100 Aeons/pound as a base for each elemental type, then adjust this price as you would for any other good, with supply decreasing it and demand increasing it.
Aether as a substance has a strange effect on a living body. It is a foreign entity of mystical and arcane power, and one that does not always play well with the extremely complicated and delicate systems of a living body. Because of this, beings that ingest highly concentrated Aether - such as breathing in too much of it, drinking or injecting liquid Aetherite, or ingesting solid Aetherite - will fall ill with a disease known as Aether Sickness. This disease lasts 1d4+1 days, and for each day of the affliction, the diseased has their Maximum Health temporarily reduced by 20%; if the disease would bring them to 0 Health, or they are reduced to 0 Health by other means while afflicted, then they must succeed a DR 18 Fortitude save or immediately die, and shortly thereafter have their body reformed into a creature, the nature of which dependent on the type and amount of Aether(ite) they ingested: Neutral Aether will create a Monstrosity, Dark will create either a Frozen or a Hollow, Light will create either a Scorched or a Radiant, Magic will create either a Fae or a Vi, Soul will create either an Unliving or an Undead, Space will create either a Buried or a Weightless, and Time will create either a Temporary or a Displaced; a Partial Success on this save will see the afflicted die but not be reformed into another type of being. Should the person survive their Aether sickness, they have a 3% chance of becoming an Elemancer of the type of Aether(ite) they consumed; if they ingested Neutral Aether(ite), the type of Elemancer they become is random.
Should an Elemancer become afflicted with Aether Sickness (which will not happen if they ingested the type of Aether(ite) that corresponds to their element), they will spend 1d3-1 days sickened (minimum 6 hours), during which time they will intermittenly vomit up whatever Aether(ite) they consumed. Should an Elemancer ingest Aether(ite) that corresponds to their element, they will immediately regain 10 Mana for every pound of Aetherite they consume, or 1 Mana every 6 seconds they breathe in highly concentrated Aether haze.
The I&A ruleset has 6 elements, all briefly described here. Each element is further divided into two sub-elements, and when these sub-elements intermingle, pseudo-elements are formed; each of these are described in full further down.
Dark. The element of emptiness, silence, the void, and all the secrets that lie within; its sub-elements are Void and Frost. Darkness is Light’s complement, and without it all would be just as blind as though there were darkness without light. Dark Aether(ite) is a deep black with occasional hints of blue, and is used to brew concoctions and enchant items that create darkness, cause silence, curse with blindness, or inflict some sort of freezing effect.
Light. The element of knowledge, of hope, of the sun shining through the trees on a beautiful day; its sub-elements are Radiance and Fire. Light cannot exist without its counterpart, darkness, as they are co-dependent on each other to maintain harmony in the universe. Light Aether(ite) is a bright white with hints of yellow and red, and is used for the creation of light-emitting enchants, particularly effective truth serums, and anything and everything to do with fire (Light and Magic together are required for lightning-based creations).
Magic. The element of illusions and power, of wonder, lies, and all which is not as it seems and does not act as it should; its sub-elements are Illusion and Force. Magic is believed to be the source of all creativity, and who is to say those who believe such are wrong? Magic Aether(ite) is purple and glimmers frequently, and is very useful in the creation of deceitful, double-natured enchants, hallucinogenic poisons, and enchants that manipulate the forces of the world.
Soul. The element responsible for everything that lives and dies, it is Soul that creates that spark that generates life in the universe - and it is Soul that necessitates that all life must come to an end; its sub-elements are Life and Death. Soul Aether(ite) varies from an ethereal green to a sickly grey, and is widely used to create Potions to restore Health and particularly deadly poisons to severely reduce it.
Space. The element of all which physically exists and has matter; its sub-elements are Earth and Air. Space Aether(ite) is clear and translucent, and appears to shift and obscure the area immediately around and behind it. It is incredibly versatile in its alchemical uses, being used in enchants that both bestow strength, fortitude, and durability, and in those that grant the ability to fly, enhance one's reflexes, or allow one to breathe safely when they otherwise would not be.
Time. Flowing ever-forward like a river, Time ensures everything in the universe keeps moving, progressing, improving, deteriorating; whatever its natural course may be, Time ensures everything will meet its destiny when it is meant to, and its sub-elements are Possibility and Reality. Time Aether(ite) is also clear and translucent, however everything around/in it seems to move a bit more quickly or slowly than it should. It is used in the creation of hasting and slowing concoctions, time-manipulating enchanted items, and items and tinctures that bestow visions of the past or future.
Each of the six elements has two distinct aspects - two sides of the proverbial elemental coin. These sub-elements represent the two halves of the whole element, creating a Yin and Yang of primordial power that, when combined, form the fundamental force of nature that is the element itself. When one sub-element "interacts" with an adjacent sub-element, that interaction creates a pseudo-element; these are explained in greater detail in the next section. Given here is a brief explanation of the sub-elements themselves, arranged by adjancency rather than alphabetically.
Light-Fire. The aspect of Light that provides heat, its presence can be both comforting and horribly painful; it is adjacent to Magic-Force, creating the Lightning pseudo-element.
Light-Radiance. The part of Light that is pure, well, light, illuminating but also blinding; it is adjacent to Dark-Void, creating the Twilight pseudo-element.
Dark-Void. The pure, unyielding blackness of Dark, blinding, but also protecting and comforting in its privacy; it is adjacent to Light-Radiance, forming Twilight.
Dark-Frost. The cold aspect of Dark, chilling to the bone and cruelly biting those caught unprepared; it is adjacent to Soul-Death, forming the pseudo-element Decay.
Soul-Death. The part of Soul that brings about the end of all living things, ensuring that, for better or worse, nothing lasts forever; it is adjacent to Dark-Frost, manifesting into Decay.
Soul-Life. The aspect of Soul that animates and bestows willpower, autonomy, self-awareness into an otherwise dull and stagnant universe; it is adjacent to Space-Earth, creating Water.
Space-Earth. A bit of a misnomer, Space-Earth does not just refer to actual dirt and soil, but all the solid physical material of the universe; it is adjacent to Soul-Life, making up one-half of the Water pseudo-element.
Space-Air. The part of Space that refers to all that which is not occupied by physical material; it is adjacent to Time-Reality, forming the ephemeral pseudo-element of Memory.
Time-Reality. That which is happening and has happened, forever part of this universe's history; it is adjacent to Space-Air, manifesting in the pseudo-element of Memory.
Time-Possibility. That which has not happened but may, or which didn't happen but could have, if things had been just a bit different; it is adjacent to Magic-Illusion, forming the pseudo-element of Prophecy.
Magic-Illusion. The duplicitous aspect of the ethereal Magic, displaying pure imagination and making fools and wonderers of those in its presence; it is adjacent to Time-Possibility, creating Prophecy.
Magic-Force. The solid and undeniable side of the powerful Magic, bending those who feel it to its will and forcing them to revel in its glory; it is adjacent to Light-Fire, forming Lightning.
All of the elements are, in a sense, related. They are the fundamental forces of the universe, derived from the same core of Aetherial energies. They are like the siblings of one big cosmic family - and much like actual siblings, some are closer with each other than others; in a sense, they are "adjacent". Picture it like this: if the universe were a wheel, physical reality would be the ring or outer edge, the elements would be the spokes, and Aether would be the axle at the center. The elements themselves they would be arranged thusly around the wheel: Light-Dark-Soul-Space-Time-Magic-Light. Where the sub-elements "meet" are the pseudo-elements, natural forces that bridge the gaps between the elements, and in so doing are an intrinsic part of both of them, hence why Elemancers are able to cast spells derived from the pseudo-elements in addition to those borne from their actual element. Each of the pseudo-elements are explained in brief here.
Lightning (Light-Fire + Magic-Force). When the pure scorching heat of Fire and the unyielding power of Force combine, Lightning is created, searing everything in its path with its might.
Twilight (Light-Radiance + Dark-Void). When the day meets the night, and Light and Dark mingle in their supposed opposition, the glowing darkness and enshrouding light of Twilight comes to be.
Decay (Dark-Frost + Soul-Death). As things approach their end, they grow cold and begin to whither away, slowly succumbing to the forces of Decay.
Water (Soul-Life + Space-Earth). Life given form and structure, Water occurs when the ethereal nature of Soul and the physicality of Space combine.
Memory (Space-Air + Time-Reality). As that which was and has come to pass fades off into nothing, solidifying its place in the timeline of the universe, it becomes as ephemeral as the Air Sentients breathe, becoming Memory.
Prophecy (Time-Possibility + Magic-Illusion). When events that may yet be project themselves onto the imaginative and gossamer nature of Illusion, Prophecy is born.
On occasion, highly concentrated Aether will go volatile, unleashing devastating raw arcane power over given area for anywhere from a couple of hours to a few days. If the type of Aether in question is Neutral, then the storms consist of a variety of reality-warping effects, such as mirages, flashes of fire and lighting, bouts of intense cold and dark, time behaving strangely, and more. Essentially, it is a smattering of different isolated elemental effects in one highly concentrated area. These storms are both deadly and disastrous for not just this reason, but also the rampant cases of Aether Sickness that inevitably follow in their wake. It is common for them to involve destroyed buildings, fractured minds, and piles of bodies in the affected area. Typically, they storms last for 1d6-1 days (minimum 2 hours) and cover up to 20 square kilometers.
Aether Storms that are not Neutral, and are instead predominantly or entirely dominated by a single element, are referred to by the name of element that they are, e.g. Dark Storm or Magic Storm. These are similar to Neutral Storms, but the arcane forces on display are constrained to only a single element, and are much more extreme as a result; additionally, they tend to be triggered when the barriers between the planes become worn thin in a given area for whatever reason, such as excessive use of that element in that area, an Elemental Incursion, or the concentrated Neutral Aether that would have become a Neutral Storm becoming tainted or flooded with one specific element in some way.
The nature of these storms varies according to the nature of the element: Light storms, for example, may involve blooms of sourceless light filling an area, fire falling from the sky like rain, lightning erupting out of nowhere; a Time storm may involve a group of people having visions of the past and/or future, suddenly growing older or younger, or isolated areas and objects skipping backwards or forwards in time. While bombardments of the element itself are to be expected, because all of the elements are, to some degree, omnipresent, the appropriate pseudo-elements will also make appearances during Elemental Storms, e.g. lightning will strike during both Light and Magic storms, heavy torrents of rain will fall during both Soul and Space storms, etc.
While Aether Storms are incredibly dangerous, they are not without their benefits, primarily in the form of the Aetherite they leave behind and the Elemancers and Elementia that each have a higher likelihood of being born if their mother is subjected to (and survives) the storm.
Antitherium is a special metal that nullifies the arcane powers and effects of Aether. Generally, when Antitherium is used to forge something or integrated into something's construction, it will nullify any arcane effects that occur inside of or adjacent to the object. For example, a building built with Antitherium will negate any and all spells cast inside it, nor can it be teleported into or out of. Manacles, shackles, or collars made of Antitherium prevent Arcanists, Elemancers, or any other spellcasting creature from casting spells entirely, depending on the placement and number of the restraints and the concentration of Antitherium in them.
Depending on the nature of the armor and the amount of Antitherium used, armor that integrates Antitherium into its construction may grant the wearer advantage or automatic success on saves against spells and their effects, as well as grant casters disadvantage or automatic failure on damage rolls against the wearer. Weapons made of Antitherium are a truly interesting case - for one, casters have disadvantage on saves to maintain Concentration when struck with such a weapon; for two, if an Elemancer is reduced to 0 Health or otherwise qualifies for a Lingering Injury when hit with an Antitherium weapon, they may suffer an effect that debilitates their ability to cast spells for some length of time, typically 1d6 days depending on the nature of the injury. Some examples of dehibilitation are: not being able to cast spells at all, not being able to maintain Concentration, having their maximum Mana temporarily reduced, or possibly even losing an Elemancer level.
For mechanical intents and purposes (e.g. blacksmithing), consider Antitherium equal to steel and thrice as expensive.