Definition
Blood magic is any magical system where blood (or more broadly, life force) serves as the fuel, catalyst, or currency for supernatural power. It creates an automatic cost structure: every spell demands sacrifice, whether from the caster or from someone else. This makes it one of the most dramatically rich magic types because the price is visceral, immediate, and impossible to ignore.
Why It Matters
Blood magic solves one of the hardest problems in fantasy writing: making magic feel dangerous. When a spell costs blood, readers feel the weight of every casting. It also raises moral questions naturally. Is it okay to use your own blood? What about someone else's? These aren't abstract debates; they're story engines.
Types of Blood Magic
Famous Examples
Melisandre and Mirri Maz Duur both use blood sacrifice for powerful, unpredictable magic. The cost is always devastating and the results are never quite what was promised.
Blood magic is explicitly forbidden by the Chantry, making its use a political and moral choice that defines character arcs throughout the series.
Shamanic power drawn from gods demands the caster's sanity and autonomy, a spiritual blood price that escalates through the trilogy.
Common Mistakes
Let the morality live in how it's used, not in the magic itself. A healer sacrificing their own blood to save a child is very different from a tyrant draining prisoners.
If your character is cutting themselves to cast spells, show the scars, the dizziness, the weakness. The body keeps score.
Establish a rough exchange rate. Without one, blood magic becomes either trivially cheap or conveniently expensive depending on the scene.
Try It Yourself
Design a blood magic system with exactly three tiers: a small spell that costs a drop, a medium spell that costs enough to make you dizzy, and a catastrophic spell that could kill you. Write a scene where your character starts at tier one and, under pressure, has to decide whether to escalate. Focus on what the choice costs them physically and emotionally.
Track every rule your magic demands
Novelium's worldbuilding tools help you define your blood magic's costs, limits, and consequences so every casting stays consistent across your manuscript.