Blood magic

Blood Magic, or Haemokinesis, refers to the control of human and animal blood, and the power that comes alongside it.

Description
Blood Magic is a versatile and powerful thing - it can save someone from the brink of death and grant them immortality with a simple blood sacrifice from the mage's own veins. It has the power to take a life in many less-than-clean ways, and it can restore a life - at the price of another. It can also be used for more practical things - such as lifting heavy objects or flying. When using Blood Magic, the mage's power is almost unlimited. Blood Magic was most commonly used by Shifters. It was considered a tool, especially for ritual practice.

Complications
Blood Magic doesn’t come without a price, however. The power is incredibly tempting once one has learned to harness it, and many believe they can get away with one isolated use. These are the people for whom Blood Magic becomes a fatal mistake. It is incredibly addictive, and even a single use without an incredibly strong will to back it up can lead to severe dependency.

The more the magic is used, the more it takes a hold of its user. It starts with a slow progression of deep purple, slightly raised veins, normally from the most often used point of usage (usually the wrist or lower arm). These veins slowly creep their way up towards the heart, eventually covering the body. The speed of their advance depends entirely on the level of usage - with every use, the veins advance, and the strength of the magic used adds to how much they advance each time.

Once the veins begin, there is also a slow decline in emotional state. Any emotional barriers will falter, and the person will find themselves more likely to snap at any given situation. They become increasingly angry and difficult to be around - often verbally and physically violent even where it is not in-character for them. This is when the decline becomes severely noticeable, as the user will be turning to Blood Magic to calm their rage, and it becomes a vicious cycle.

This decline will continue, until the person is barely recognisable - even to those close to them. They will then begin to physically alter; the veins now covering their body and their eyes turning pure black - no whites. Their nails will form claws, and their teeth sharpen; often ragged, bat-like wings will sprout painfully and messily from their back. By this point the change is all but irreversible, and they are doomed to become a mindless abomination; first attacking those closest to them, and then branching out and killing until they themselves are killed.

Restriction
It is highly recommended to kill a Blood Mage in the physical mutation stage. The final stages of the change are incredibly difficult to cure, and only a trained team of mages with forms of necromancy, black magic, and/or blood magic themselves can even hope to reverse it. It is possible for other entities and beings to cure it, but rare.

This is why the Shifters soon learned to restrict their use. With the increase of abominations, casual use was outlawed and only spiritual Elders, those who have lived a full and experienced life, could use it. When the corruption inevitably overtook that person, it was down to the most revered warrior in the clan to kill them, and the Blood Mage’s apprentice to remove the demonic influence and put them to rest before they could cause havoc.