Blood Magic

The idea of sacrifice with respect to magical power is nothing new. Even the most basic function of spellcasting consists of developing a reservoir of accessible power, which is sacrificed to fuel the casting of a spell. In this respect blood magic is no different, and its originator, Solomon, knew this.

Desperation

In the wake of the Shattering of the World, things were dire for the Dwarven people. The giants and their goblinoid minions had engaged in total war, beating back and enslaving the dwarves through sheer force of numbers and a desperation borne of terror. It is small wonder, then, that in such desperate times Solomon would turn to such dangerous magic to help grant him whatever advantage he could to help defend himself and his people.

The most famous of his spells, and easily the most widely used, is a spell known as Solomon's Armor. It uses the life force of the caster to make a far more durable, longer-lasting, and difficult to dispel protection. This isn't the only spell that operates on Blood Magic, but it is a good example of the mechanism.

Dark Origins

The power of sacrifice, of making direct use of the life force and possibly soul of a sentient being, has a dark history that begins with the powerful necromantic abilities that create undead from the body and souls of (once) living beings. The origins of Blood Magic came from Solomon's research into the possibility of becoming a lich, and the possibilities created by a magical reservoir such as a phylactery.

Choosing instead to focus on the inherent power of life force, blood magic allowed Solomon to empower his spells to help his fellow dwarves defend themselves and take back the delves from the giants and their minions.