Blood Curse

'Blood Curses are a raw and evil form of magic only capable of bringing further death and destruction.' - Alexanda Daltech expert on curses and dark magic

A Blood Curse is a particularly potent form of curse which is almost always malevolent in nature.
Blood Curses are suffering incarnate, unlike most forms of magic they draw their power from pain, blood, and death. The most powerful form of Blood Curses are those cast by a creature's dying words. The most prominent example being Havdar's Curse.
A person need not have a preexisting ability to cast magic to invoke a Blood Curse, any person with hatred, vengeance, or pain in their heart can invoke Blood Curse. They are often invoked during executions, where a person seeks to achieve vengeance from beyond the grave.
Examples of Blood Curse include:
Afflicting a person with Therianthropy or other supernatural disease.
Causing a supernatural disaster, such as the Havdar's Curse.
Casting a high level spell to devastate the surroundings.
Raising a large number of undead.
Opening a portal to another plane of existence.