Spirits

A spirit is a supernatural, incorporeal creature that does not take up space from normal mass. Instead they are lifeforms composed of  etheric matter, which does not interact with everyday matter in most cases, only other ethereal manifestations. As such, they can be touched/harmed only by other incorporeal creatures made of etheric matter, magic weapons or spells, mana plasma, or supernatural/preternatural abilities and objects that orginate from their home dimension: the ethereal plane.

Spiritual Matter and Energy

In this post, Spectral=spiritual but spectral sounds cooler.

Etheric is immaterial matter that doesn’t interact with normal matter and in most cases light. Interestingly, it does have some weird version of mass as it drifts within gravitational fields of normal celestial bodies and definitely those also of etheric substance. As such in the contemporary eras, it is speculated have counterparts to everyday materials and energies.

Spirits are beings composed of etheric matter which while intangible with normal stuff, can at least interact with itself, meaning spirits can touch ethereal objects, materials imbued with etheric energy, and be affected by spiritual energy psychokinesis (PKE). Unlike most corporeal beings, their mass can often behave similar to fluids (like liquids and gases).

* The idea was influenced a bit by dark matter, mainly the not interacting with baryonic matter part, but I wouldn't go far as saying that spirits are made of dark matter in story. Although I have been playing around with the idea of spectral comets and asteroids.

!Biology

A spirit possesses the following traits (unless otherwise noted in a creature's entry).
 * Incorporeal : All spirits have the incorporeal subtype when not possessing or manifesting a physical body. They are composed of etheric matter, a type of matter that normally doesn't interact with normal matter or visible light, typically being invisible and passing through unnoticed. They are most commonly composed of a type called ectoplasm.
 * Possession : All spirits can possess physical objects or creatures. However the exact kind of object or creature a specific spirit can possess is noted in the creature's description.
 * Corporeal Manifestation : Some spirits can instead manifest as a physical creature to interact with normal matter. The exact kind of object or creature a specific spirit can manifest as is noted in the creature's description. The manifestation no longer is incorporeal, thus it is affected by normal matter but now intangible to etheric matter from the ethereal plane.
 * Arcane Magic : All spirits are capable of performing ordered spell-craft as well as have innate magic qualities unique to their kind called supernatural abilities. This includes those with spirit ancestry.
 * Psychic : Spirits can produce psychokinetic energy, but what specific ability it manifests will depend on the being and will be displayed in their entry. Typically:
 * 1) Telepathy : Transfer of information on thoughts or feelings between individuals mentally
 * 2) Precognition : Perception of information about future places or events before they occur.
 * 3) Clairvoyance : Obtaining information about places or events at remote locations.
 * 4) Psychokinesis : The ability of the mind to influence matter, time, space, or energy.

Feeding Another aspect of spirits, is that to be able to manifest and survive on a physical level, they require sustenance. Some feed off of Environmental essence through scents, some off of blood, some from pain, others from tears, and the more dangerous type feed from souls but most feed from the essence of the land, it's elements, and it's people. Some spirits required small gifts, and prayers to sate them, or they would become hostile and dangerous. These gifts, and the worship, 'fed' the spirit.

In their physical forms however, spirits can feed themselves like non-spirits through various organic matter but their diets are usually constrained to the diet of the being they manifest as.

Spirits do not need to breathe, eat, excrete or sleep (although they can do so in a corporeal form if they wish). Spirits possessing a creature are subject to the physical needs of that creature.

Manifestation

The majority of spirits have developed various means of manifesting a form into the material plane that can interact with the everyday physical world.

Direct Approach To manifest a physical from that can interact with normal matter, a spirit has a number of options. The most draining of energy - and direct means - is to simply appear in the physical world. This is the main way that Deities and Jinn choose to exist.

Possession The second option is to possess an object or an aspect of nature they are naturally associated with. This is most common for Dryads, Elementals and Yukionna who are already the spiritual counterparts of various aspects of nature like rivers and specific places.

Avatar Method The third option is limited to spirits associated with living beings like humans or animals and it involves possessing them, either very young, or unborn. This method was the least taxing on the spirit, and resulted in a hybrid of the spirit and the person/animal/plant possessed. If possessing a infant creature, the full possession takes longer, but if pre-born, it's instant.

Damage and Death A spirit, depending on how they have manifested, can be harmed in different ways. One who just manifests is capable of rapid regeneration, healing most wounds in almost no time, and developing resistances to most normal weaponry. The exception to this is if they are struck by a blessed object, or a magical object. Such attacks can cripple or outright slay a manifested spirit, forcing it to return being a spirit, or, if powerful enough, destroying it permanently by reducing it to inanimate etheric matter.

Spirits who are possessing someone are in a better position.

The physical body can be attacked or killed, but the spirit can simply leave the body at any time, leaving the hapless victim to suffer whatever fate was meant for the entity. To harm the etheric being requires a blessed or magical weapon, meant to harm spirits.

Spirits who have taken avatars are very vulnerable to physical harm. Anything that can harm a corporeal can harm the spirit. These spirits do not passively regenerate like others, and must either spend their resources like arcane magic to heal, or heal at a natural rate. Magical weapons and faith will harm them far less than other spirits, because they are accepted as more 'natural' to the physical world, having become even more attuned to it then as nature spirits. These spirits, once killed or die, also re-animate as spiritual aether but much weaker than any other of their brethren.

When a typical spirit as been killed, unless their spirit has been destroyed, they have a number of options. Depending on how recently and how much they have fed, they can re-manifest in any of the listed ways.

If they do not, or can not, remanifest, they can just wander the world as spiritual wisps, biding their time and waiting for the most convenient time to do it.

While in their spirit forms, the entity is immaterial and can pass through most kinds of matter but is very vulnerable to spirit attacks or magics.

Jinn  ( Sub-type ): Jinn are spirit creatures different in that instead of representing or embodying a concept, they are have completely independent natures like people and of the natural world if they choose. Also their spirit forms can be influenced by strong electric and magnetic fields due to their etheric energy interacting with electromagnetism in a similar fashion to plasma.
 * Djinn
 * Ghul
 * Hinn

Divine  ( Subtype ): Divine spirits are distinguished by having " vastly more power than the average mortal " as they are the only beings capable of performing Divine Works. They are also immortal by either simply preventing such damage from appearing (invulnerability/protection), while others are the regenerative type, surviving and quickly recovering. Many also manage or guard an aspect of either natural, preternatural, or supernatural mechanics of existence.
 * Deity
 * Angel

Demonic  ( Subtype ): Spirits that originate from or corrupted by Negative Mutagenic Ectoplasm. As such their motives are typically described as evil and threats to most forms of life. Generally they focus on corrupting other forms of life to join them or eliminating the competition.
 * Devil
 * Fallen
 * Obakemono
 * Hell hound
 * Hellish Horse