Aura

Aura is the combination of the energies Animura and Corpura and can be used for a wide range of abilities. The specific abilities and their strengths differ from individual to individual and are dependant on a number of factors, such as experience, training and innate skill.

It is predominantly used for protection from harm. Some people develop a special power called Semblance.

Animura
It is the main and most complex type of energy conforming the aura. It is described as the manifestation of the soul, meaning it is directly linked to the soul of a living being. It is known that every living being in Remnant possess it, including animals and grimms.

This energy is capable of healing the user and keep the soul inside of the body. The animura is an almost unlimited ammount of energy but it can't be used at will making it impossible to be exploited.

Corpura
It is a secondary but still complex type of energy, surpisingly being compatible with the Animura. The time of origin is completely unknown but it is said that humans and faunus developed it as a defensive system to confront an hostile world. Only humans, faunus and species created with their DNA like lycans, vampires and the homunculus possess it naturally though it is known that it can be transferred to other living beings for aid with the exception of grimms thanks to their nature, or experimentation like the case of the adtigences Penny and Buck.

This energy is capable of forming a basic shield around the user and it serves as fuel for the semblances in most of the times. When someone deplets their aura actually means that they have depleted their reserves of corpura as it is a limited energy until it can recover again.

Description
As half of the energy componing the Aura is liniked to the soul, it can manifest in different colors since it differs from person to person.

Skilled users of Aura can create their own barriers or even increase their own abilities in some way. Weapons and armor can also act as a conduit for Aura, allowing for an even wider range of offensive and defensive capabilities. This even applies to nontraditional "weapons", such as a loaf of bread or a leek.

It has been shown that the strength of an Aura degrades with continual use. This limits the applications of Aura in combat as, with time or heavy use, a person's Aura will decay to the point where they are left weakened or even incapacitated. Aura being completely depleted is visually represented as a colored sheen glowing along the length of a person's body or with colored particles flying off the body, indicating that they can now be physically injured. Aura flickering means it is close to being depleted. This is mostly caused because of Corpura since it is linked to the body of each user. Aura can be recharged and the time it requires to recharge is varies between each person.

Aura also can vary between individuals in terms of innate quantity of energy that can be used, this is determined by the category of their semblance (no matter if it is still locked) being legendary the one with a biggest reserve of aura.

The powers of a Maiden are said to tied to Aura, until death of the indiviual which causes the power to separate from their Aura.

While those using robotic prostheses such as Yang Xiao Long and James Ironwood are apparently able to shield their artificial anatomy with Aura, those who use Grimm transplants are not, due to their different nature and biology.

Abilities
Aura is a necessary energy source for all Huntsmen, being a powerful ally in battle, can be used in the following techniques:
 * Defense: Aura is mainly used for defensive purposes, while users of Aura will not be hurt as long as their Aura is up, they can still feel sensations such as pain and heat. It requires training to always subconsciously have a cloak of aura on.
 * Offense: With advanced training, user can shape, harden or separate aura. An example of this could be a shockwave or a barrier.
 * Unlock Aura: One's aura can be used to unlock the aura of someone else. However, doing this take a toll on the user.
 * Healing: Aura can heal minor and average wounds. However, the healing is automatic and not caused at will.
 * Extrasensory Perception: It is known that aura can be used to register irregularities in the terrain, also to orientate and balance the user in case of blindness.
 * Climate Protection: One's aura can protect from cold and hot weather. As with combat, extreme weather will deplete one's aura.
 * Sensing Aura: With proper training, the user is capable of sensing other's aura, manifesting with a feeling of being watched from a certain direction.
 * Identifying Aura: With enough training the users are able to identify specific auras.
 * Semblance: It is the projection of Aura into a more tangible form. These are reliant on person's aura reserves to be used, in which they are unusable if a person's aura is depleted.
 * Transfer Aura: When transferring aura, the user is actually just giving corpura since the animura can't adapt to any body and even if it could, an user can't simply give it.

Activation
It appears that Aura is able to manifest in different ways when in use and takes on the color of one's inner energy. It appears as a slight glow around the body. In the past as people needed it to survive, it was activated from their birth but due to most of the population having a comfortable and stable life, it is locked. It has been stated that the activation of an Aura requires training and willpower, though someone with considerable training can unlock the Aura of another person.

Capture
The Kingdom of Atlas has been performing serious scientific research into the nature and composition of Aura. Their research has yielded experimental technology that is capable of "capturing" Aura from a person and transferring it to something or someone else. The existence of this technology is highly classified, but many of those who do know of it view it as ethically immoral and wrong. Regardless, this technology was intended to play a key part in preventing the Fall Maiden power of Amber, whose power is linked to Aura, from falling into the hands of Cinder Fall by unnaturally transferring the powers to Pyrrha. It is stated that if the plan was successful, it might have unknown effects on Pyrrha's psyche and personal identity, merging them with that of Amber. Cinder preempted the plan by killing Amber before the transfer could be completed.

A derived technology to create vessels capable of holding aura as if it was a living body led to the creation of Penny and Buck, the first synthetic people to generate an Aura. Though it was possible thanks to Pietro's Semblance which allows him to transfer animura, and since it is natural he was also able to tranfer corpure creating a completely new and kind of artificial soul as well as ability to continue generating both energies independently.

It is known that the Covenant is also capable of creating an artificial soul, as demostrated with the creation of the homunculus, Flame Fall, in this case as surprising as it sounds, they created a machine capable of extracting the residual animura remaining in fresh corpses. A similar method was used by Ozma in the creation of his own homunculus but using his magic to extract the animura.

Vessel

 * Human Body (Remnant): As the aura's origin is with the humans, everyone from this specie is capable of holding it. Other kinds of humans like the ones of the first wave or the natives from Paradise Hell are capable of holding aura but don't generate it.
 * Faunus Body: As the aura's origin is also with the faunus, everyone from this specie is capable of holding it.
 * Homunculus Body: This case only applies to homunculus created with DNA from humans or faunus, being that the reason why the Brainperor doesn't have an aura.
 * Vampire Body: As descendants from the homunculus Lanfear, and because of their nature as humans or faunus while still being alive they are capable of holding an aura but suffering modifications.
 * Lycan Body: As descendants from the homunculus Dylan, they are capable of holding an aura.
 * Adtigence Body: This is only possible if the body of the adtigence was built specifically to hold an aura and generate more on its own, like the case of Penny and Buck.
 * Eidolon Body: A research made by Sam, proved that Eidolones could generate an aura of their own but only after fuse with the soul of a human.
 * Aura Container: Thanks to Atlas' investigation, they created technology capable of holding aura and even being capable of transfer it to other beings, with some collateral damage.
 * Human Body (Remnant) Fused With Phalloid: In case a phalloid fuse with a human through symbiosis, it is capable of using aura.
 * Faunus Body Fused With Phalloid: In case a phalloid fuse with a faunus through symbiosis, it is capable of using aura.  
 * Vampire Body Fused With Phalloid: In case a phalloid fuse with a vampire through symbiosis, it is capable of using aura.  
 * Lycan Body Fused with Phalloid: In case a phalloid fuse with a lycan through symbiosis, it is capable of using aura.  

Rules of Preservation

 * 1) In order to unlock a semblance, the user must have both energies in complete balance, meaning that if one is missing, the activation of the semblance is completely impossible.
 * 2) A corpse is capable of continue generating corpura if reanimated.
 * 3) A corpse retain animura remainings for around 3 hours depending on the environment, if the owner's soul is able to return to the body in that time, their animura will attach the remainings and keep working like it has always done.
 * 4) If deceased and the soul can't reach the body before the animura remainings dissipate, it still is capable of merging with their body if the corpse was perfectly preserved and kept functional (for example, it won't work if the organs are missing).
 * 5) In case the soul can't reach the body in the limit time and the corpse wasn't preserved it can use an alternative of merging with a cloned (compatible) body but suffering from modifications.
 * 6) If a soul merge with a compatible body after the time limit, the aura will continue to work but both energies won't be in balance anymore, making impossible to unlock a semblance but gaining extraordinary regenartive abilities as there isn't the resistence the corpura created.
 * 7) Vampire souls are kept in their body by force, being that the reason why their body is still dead even if they already merged, in case a normal resurrection is applied instead of vampirism, their body will live again, meaning they can die again.
 * 8) If technology is used to transfer aura between two people, it will cease with the giving part and add the aura to the receiving part but with the collateral damage of fusing personalities, frequent migraine and don't have a total control over the aura, this in case the receiving part had enough room for another aura.
 * 9) If a vessel exceeds the ammount of aura it can handle for a few seconds, they will suffer of spontaneous combustion.
 * 10) A body without animura can't work at all since it is what keeps it alive meanwhile a body without corpura makes the user uncapable of using aura at all, also since the animura always look for the compura to detect a body as alive, it won't heal the user as the own animura thinks the body is dead.
 * 11) Animura could accept magic as a substitute to corpura, though nothing bad happens if a body posses animura, corpura and magic.
 * 12) If aura is cancelled on purpose, none of the abilities will work, including the automatic ones like healing or regeneration.

Integrated Semblance
An integrated semblance is a special case when a person is capable of unlocking two or three semblances instead of just one.
 * Double Semblance:When this happen the user's body suffer a modification that allow them to hold the double of aura but the aura is separated in two parts and assigned to each semblance.
 * Triple Semblance: When this happen the user's body suffer a modification that allow them to hold the triple of aura but the aura is separated in three parts and assigned to each semblance.

Madhouse Semblance
The madhouse semblance allows the user's body to be the host of other souls that are brought by force from the afterlife, it has also proved to be able to drag Eidolones if they are weakened.
 * One soul: The user is able to have one extra soul in their body as it suffers a modification to hold two different auras and the semblance is in charge of no letting the two animura fuse.
 * Two souls: The user is able to have two extra souls in their body as it suffers a modification to hold three different auras and the semblance is in charge of no letting the two animura fuse.
 * Three souls: The user is able to have three extra souls in their body as it suffers a modification to hold four different auras and the semblance is in charge of no letting the two animura fuse.
 * Four souls: The user is able to have four extra souls in their body as it suffers a modification to hold five different auras and the semblance is in charge of no letting the two animura fuse.
 * Five souls: The user is able to have five extra souls in their body as it suffers a modification to hold six different auras and the semblance is in charge of no letting the two animura fuse.
 * Six souls: The user is able to have six extra souls in their body as it suffers a modification to hold seven different auras and the semblance is in charge of no letting the two animura fuse.
 * Seven souls: The user is able to have seven extra souls in their body as it suffers a modification to hold eight different auras and the semblance is in charge of no letting the two animura fuse.
 * Eight souls: The user is able to have eight extra souls in their body as it suffers a modification to hold nine different auras and the semblance is in charge of no letting the two animura fuse.
 * Nine souls: The user is able to have nine extra souls in their body as it suffers a modification to hold ten different auras and the semblance is in charge of no letting the two animura fuse.

Semblance Power Category
Depending on the power category of someone's semblance, their aura reserves are bigger. Which means that someone with a low power category have more empty space to fill with received copura than someone with a legendary power category.
 * Positive and Negative Legendary Category: As the most powerful semblance users, their aura reserves are bigger which means that their body can't handle much external aura besides their own.
 * Positive and Negative Very High Category: As the second most powerful semblance users, their aura is notably big which means their body can handle with a bit of external aura besides their own.
 * Positive and Negative High Category: As powerful semblance users, their aura is big which means their body can handle a respectable ammount of aura besides their own.
 * Positive and Negative Neutral Category: As average semblance users, their aura is of an average reserve which means their body can handle immense ammounts of aura besides their own.

Chosen One Vessel
There is an unlikely but possible case of an user having a triple semblance and one of those semblances be the madhouse semblance of nine extra souls and that each soul inside have triple semblance besides each one of the semblances being of legendary category. This almost mythological vessel will be granted with:
 * Capability to ten animuras.
 * Capability to thirty corpuras.
 * Enough room to thirty legendary semblances.