Blood Magic: Creating a Hard Magic System

I've been doing some sketchy Google searches, recently. I'm worried that the FBI might have me on a watch list, now. As you may or may not know, depending on whether you've been watching my streams on Twitch or not, I'm developing a magic system for my comic. I'm developing what is known as a "hard magic" system. Think Full Metal Alchemist magic: there are strict boundaries and limits on what the alchemist/caster can do. A "soft magic" system would be more like The Force, where you can do pretty much anything with it and the limits aren't particularly clear.

So... The magic system I'm developing uses blood as the main component for spells. Because of this and because I want fairly strict limits, I've been researching how much blood the human body has, what different levels of blood loss will do to a human, and how quickly a human can lose blood. In case you're wondering, a human can bleed to death in as little as 20 seconds. Pretty terrifying... But my research isn't purely for morbid curiosity! I've decided that, to cast a spell with "Blood Magic," one cup of blood must be expended, limiting a caster to 10 spells before they pass out/die. One big spell that I've settled on is a Blood Sword spell, where the caster uses their own blood to create a sword. The sword must continually get 1/2 a cup of blood every second to sustain it, meaning that you have 10 seconds of safe use time, 20 seconds if you're desperate.

The feature of my magic system that'll separate the good guys from the bad guys is where they get the blood from. Obviously (probably), a good guy isn't going to want to use someone else's blood to cast a spell. Bad guys, however, will probably avoid using their own blood and use blood that they've collected. I intend to depict this later on in the comic, but I'm going avoid being Berserk gory with it. Leave it up to your imagination more. I'm working to create a truly terrifying set of bad guys that'll make everyone super uncomfortable.

Well, wish me luck and thanks for reading!