Vis

Vis (Vibrant Internal Source or V.I.S.) is the energy of otherworldly force. Springs or Pools of Vis are accumulated when mortal creatures die. After their soul leaves their body, their remaining essence flows from their corpse. This is why undead can't cast magic; they no longer have the ability to tap into the magical energy. Vis is all over the world. However, one can't use a single strand of Vis; it can only be harnessed when a Pool of Vis is created. Once someone comes in physical contact with a Pool, they can then cast magic. When someone casts a type of magic, it is the act of turning this Vis into physical energy and force.

Vis can be regenerated over time when not being consumed. When a mortal becomes a host of the energy, it stays inside them until they become a corpse. The exception of this are those that are undead, though they have their souls and minds intact (e.g. vampires and certain undead); once they are destroyed, the Vis disappears into the realm of Xieahr. Once a host becomes a corpse, the Vis flows from the body, scattering the world, in search of more Vis to merge with.

Origin of Vis
Vis has a few theories of creation. One of these is that the Baht Fiend, Ploahh created it to further extend his legacy of knowledge. Another is that the Baht Shade, Niosebil left behind lingering pieces of his soul that could be harnessed into energy. The most likely theory is that it was created by Mortis. After the battle between him and Vitis, he had left traces of it behind in Gahram. Legend says that the Vis was dormant until death, meaning that mages appeared later in time. Other humanoid mortals would sense the strong energy in the atmosphere as it merged and grew. The first mortal in history that came upon the Vis and channeled it into physical energy was the Highscale, Aros Makailen.

Concentration
When a spellcaster concentrate on a specific school of magic, the Vis inside them adapts to using that school of magic, just as a muscle would adapt to a certain exercise. This would make spells in that school easier to cast. The downside is that it gives the mage the difficulty of going from one school to another; a very skilled healer would have trouble casting powerful fire spells or conjure a spectral sword. However, it is still possible to learn other schools. Novices and student mages are able to cast a variety of weaker spells because of their Vis not fully focused on one class.

Replenishment
Vis is naturally self-replenishing, though many spellcasters prefer to speed up the regeneration. Here are ways one can do that:
 * Via a Pool of Vis
 * Drink potions that restore Vis
 * Certain meals by exceptional cooks can have certain Vis regerating effects
 * Via weapons that drain Vis from a spellcaster
 * Wearing certain clothing or armor that increases Vis replenishment
 * Wells of gathered Vis in magispires

Items

 * Magic circlets quicken Vis replenishment
 * Mage robes quicken Vis replenishment and/or lower the cost of Vis
 * Magic staves lower the cost of Vis
 * Magic sceptres lower the cost of Vis
 * Paladin swords
 * Shields and armor absorb bits of Vis

Purification
The Paladin Order sees spellcasters as menaces of the Divines (although, the Divines that the Arcani worship and the ones that Mundi worship are different). A Purification Service is stripping a spellcaster of their Vis directly and permanently. This Service is only known to be only done to Arcani, as they are the most likely to become dangerous.