Soul

Soul is the term to represent the incorporeal essence that is part of every inhabitant be it alive or dead who have it in Xostya. It would also seem to act as different fuels for the successful casting of both Resurrection Magic and Wild Magic respectively. Wild Magic itself is powered by souls.

Overview
All living and some undead creatures are known to possess a soul in their own body respectively. What represents the souls are believed to be the "minds" of individuals. There was even a job-changing item known as "The Soul of Cainabel's Blood" which allows a person to acquire the Blood Soul class. One of Xostya's books, Book of the Dead was about transforming the dead into souls. With Xostya origin, it details how souls are entities.

Although people get themselves killed due to incidents or events of various wars between countries, their souls don't simply vanish after dying. Instead, it will leave the bodies, continuing to linger on in the location where they have ended up dying. Each bearing resentment towards their former life, the many souls lingering about in any area can lead to the birth of more and more negative energy to steadily rise and converge. Hence, priests are often sent out to scout areas and use their spells for ceremonial prayers to cleanse their surroundings of undead. They have done so to purify the departed souls roaming about in a particular area heavily influenced by negative energy. If the negative energies are proven to be large-scale, massive prayers will not be enough to rid all of it away.

According to the priests' religious viewpoint, souls resided within the body of every living being in Xostya. A fleshy human body, for instance, served as nothing more than a mere vessel to keep the soul contained in it. When any one of these bodies begins to rot, that soul would be summoned away by the will of the Four Great Gods. That was why the dead had to be buried immediately, with underground burial as the norm, but it was slightly different for those with special status such as the nobles. Hence, the place where the corpses were laid to rest was the space of the communal crypt or the noble's family crypt. After placing the bodies there for a period of time, the priests would judge if the body was rotting and the soul had been summoned by god before burying it.

Other than this religious principle shared among priests, they theorized that the undead entities are responsible for the corruption done to the souls of the dead.

While so, native denizens of Xostya would solemnly clasp their palms together to respect their fallen loved ones, praying for the souls of the dead during ceremony-type memorials or burials.

Mechanics
As the living and specific undead creatures have a mind of their own intelligently, so do the souls which are bounded to each one of their bodies before death. It could be said that instant death magic lies in the Departed Souls System of Magic. However, it should be noted how there were other magic systems that hold instant death effects. For example, the Spiritual system magic also have it apart from that one magic system involving departed souls. When a person with a strong soul dies, their soul will depart from the body which in turn later gets swallowed up by a world of invisible darkness they cannot perceive beyond the afterlife. In that kind of world was presumably where only the fallen ones' minds often tend to reside in and faintly think about without self-identity or awareness while immobilized. Nonetheless, any one of the souls can be brought back to the living as long as its physical body or corpse is present for someone to use Resurrection Magic on. However, third-party magics like [True Death], a 9th tier spell can invalidate such a revival process from happening between body and soul connecting together. It's noted that in order for a resurrection spell to take effect, it must be applied or used on the soul rather than the corpse. Without an intact corpse too, there is a chance that using revival magic improperly might cause the body to turn into one of the undead.

Meanwhile, Demons have the capacity to grant any wish in return for any person’s souls while the equivalent exchange is made between both sides. For starters, a demon could be transformed into a beautiful woman as part of that individual's deal before laying claim to their soul. A Succubus is a prime example of consuming the souls of men through sexual acts with their soulmates. Devils can even steal souls from the individuals they made contracts with accordingly as promised. Particularly, the demon Overeating could consume the souls of foes to reproduce their victims' screams that would terrify and kill any other living creature out there. In a way, the demon's abilities can go as far as to induce fear to a person's soul if they are not protected with items or counterspells against its effect. One of such demonic abilities is [Soul-Bought Miracle], which has special origin hailing from Xostya. It was the kind that happens to be inspired by stories of selling off one’s soul to the devil for the sake of fulfilling one's wishes. It was believed that conjuring forth demons from the Demon World to Xostya will stain the summoner's soul.

Let alone the summoning of demons, the same could be said with any person who attempted to create undead minions under their command. Likewise, creatures of death who bears great hatred towards life or the living was considered as an act that defiles their summoner's soul as well. Some undead monsters out there benefit greatly from the consumption of souls, thriving from it to help bolster their ability or power. For instance, this would include the Death Knights and Soul Eaters that possessed capabilities correlating to the souls of their foes. It was said that any person who gets themselves killed by the Death Knight’s blade would turn into the monster's undead servant. What became of their souls were in fact, slaves to its master for the rest of eternity. Additionally, there was Soul Eaters who consumed the souls of the living in order to grow stronger. They could also consume the souls of the dead for sustenance to increase their power the more souls they ate each and every passing time. When a more powerful Undead uses an [Undead Domination] skill to take control of its weaker undead foe, the latter's mind and soul will cave into its effect, resulting in their acknowledgment of the user before it as its master.