From the introduction: Blood magic pulls from the magic that flows through the blood of every living creature. Although sorcerers are most famous as those who turn the power hidden in their blood into magic, other spellcasters can use this power as well. Most of these spells utilize or change a body’s hemorrhaging life force—either that of the caster or of the caster’s target—and therefore are necromancy or transmutation spells. But blood magic is flexible and fits into many different schools.