Animus

The Animus is the "soul" of a creature native to Ikarthia, composed of intricate magical patterns.

Arcanic Science
The Animus is a repeating, self-propagating pattern of magical vibrations that are imperceptible to almost any form of magical analysis, appearing as a solid line on the magical spectrum. This pattern falls within the Wizard's Range for normal demihumans. This vibrational pattern contains the entirety of the information necessary for reconstructing the creature's physical form - everything from their inherent potential for magic, to the color of their eyes, to their physique and body type. This pattern is completely immutable under normal circumstances, and permeates every part of a creature's body, infusing them with life essence.

Anatomy
The Animus is stored in the blood. The composition of an Ikarthian creature's blood contains trace amounts of a hemotine crystal structure, which stores the vibrational pattern. This pattern is present, in one form or another, in every living creature native to Ikarthia - even plants and insects.

In the event a creature's Animus lacks the necessary level of magical energy to keep them alive, their body will unravel into the elements that originally compose it. This is a rare sight and tends to mainly end up being spellcasters who massively overexert themselves.

Impact on Civilization
The presence of the Animus within living creatures in Ikarthia, specifically of those that fall within the Wizard's Range, results in magically inclined individuals becoming capable of terrifying and awe-inspiring feats.

Interaction with Vampirism
When a creature contracts the Violet Plague, their animus is irrevocably modified by the disease. While previously thought to be impossible, the modification grants the creature incredible strength, reflexes and durability, as well as the ability to innately create certain magical effects. The massive downside of these modifications is that they all require magical energy to fuel themselves, and it feeds directly on the creature's animus when used. Naturally, this invokes a bloodlust in the creature - the magic within their blood is failing, and they must source it from another living being. This condition is known as vampirism.