Bloodmagic is the darkest form of magic known. It involves the usage of life force, blood, and suffering as a source. Bloodmagic is the magic of the Crimson King, and therefore its usage strengthens Its power as all bloodmagic sacrifices are made to the Crimson King. However, the existence of the Crimson King is a closely guarded secret, both by Itself and Its cult, and as such most Blood Magicians do not even know the ramifications of their art.
The primary fuel of bloodmagic is the very essence of life itself, or the soul, and as such it is unpredictable, dangerous, dark, and cruel.
Bloodmagic has a variety of uses, from prolonging life, "resurrecting" the dead, creating diseases, creating curses, and much more.