Mana is one of the major sources of magic in Odiem, the other being the power of the deities. It is a physical concept, largely made up of a crystalized liquid, although it can exist in solid form as well.
It is the result of all biological interactions between living species, as a sort of byproduct. It was formed thousands of years before the Primordial Age, and has since crystalized underneath the surface of Odiem.
Mana begins its life as an invisible, microscopic crystal that floats in the air. These crystals are harmless to the health, and are always very sparsely distributed in the atmosphere, meaning that the chances of actually breathing one is very low.
Similar to how carbon dioxyde is a byprodut of respiration, Mana Crystals are formed as a byproduct of emotions that two living beings can have for each other, such as love or hate. Every time a living creature loves or hates another, its body will produce a few crystals as a result of its brain producing certain chemicals.
Over time, these crystals deposited themselves into the earth, and accumulated for thousands of years until they formed rivers and large crystals. The vast majority of these rivers are found underground, although there is a massive mana river known as the Mana Spool within the island of Fiyo Thalore. The Mana Spool is 573 kilometers long, and it's the largest exposed vein of mana in Odiem.
The beings that dwell in these rivers are known as Spirits, and they are made up of pure Mana. They are not as powerful as deities, but they are able to magically alter their surrounding and even teleport to other veins of Mana. They are also not able to produce offspring in the same way deities can, instead reproducing by simply appearing and disappearing into the Mana rivers.
Every living creature has some trace mana in their bodies, which is imperceptible and incapable of producing any heat or magic. Every time a mana infused object comes into contact with another, the mana will rapidly travel from one body to another. So with that in mind, every time a person touches another, their bodies are exchanging mana.
Because the amount of mana in a person's body is so low, this always goes unnoticed. Even in creatures with higher mana like the thalorans, the contact is not harmful, however mana does make their body warmer than the average arimphean individual. If a thaloran touches a human, the human will feel a mana rush entering their body, which quickly dissipates, and the human will feel a brief but pleasant buzz, almost like a high. The same occurs when a minor deity touches a human, albeit the high is more intense and lasts longer.
However, if a mortal touches a stronger source of mana, like a mana vein or the body of a True Deity, the amount of mana entering their body would be so high that they wouldn't be able to survive. If a mortal were to touch the sun, their body would simple burst at the seams with the amount of mana it would receive.
It is possible to contain and handle raw mana with certain materials, like gold and platinum metals. It is also possible to be ingested with distilled in a solution of aqua vitae. Commonly, the best practice to distill it is one part of raw mana for ten parts of aqua vitae.
Aside from retrieving mana directly from a liquid mana vein, it is possible to use the bodily fluids from the deities. From those, many scholars have agreed upon four main fluids, which are called the divine fluids. These fluids can be dilluted into magic potions and ingested by mortals. Theoretically, any bodily fluid from any magical creature can be used, however the fluids from True Deities are the most powerful and thus the only ones that generally have an effect on the body.
The fluids are separated into "warm," "cold," "strong," and "weak." The difference between strong and weak is merely they efficacy, since even the weak fluids are strong enough to kill a mortal if ingested without distilling it first. Warmer fluids are also stronger than cool fluids.
Blood: warm and strong. Blood is perhaps the strongest fluid one can procure from a deity, and thus the most dangerous. It is also the most difficult to obtain since deities very rarely offer their fluids willingly, especially their blood.
Semen: cool and strong. This is easier to procure than blood, but still extremely powerful. All true deities are capable of producing semen, unlike minor deities, in which some are unable to.
Urine: warm and weak. It was believed that deties do not need to drink water, however in many cultures offerings of food and drink are common to deities, who seem to consume it with no problem. Urine is a very rare fluid to obtain from a deity, but it is possible as they do need to urinate from time to time. This is the only known method that a deity can eliminate waste, and it happens very rarely. Thus, it's not used often.
Tears: cool and weak. This is the weakest but also rarest of fluids. Tears are easier to ingest because they are already somewhat distilled, some beings such as thalorans may be able to drink pure deity tears without the risk of dying.