How would magic work if magic was fueled by murder?

***Possible Spolier Alert: This concept was inspired by the anime "Attack on Titan" and other anime and manga I've read. I understand this is not an unique concept, so feel free to add your thoughts on how this type of concept has been depicted elsewhere.***<br><br>&#x200B;<br><br>This is a story I'm working on. Magic is fueled by your spiritual energy, which most people have a small amount of, enough for just basic spells like a quick shield or healing. Spiritually is a replenishable resource, but as it is for most people, it is too limited to be used for bigger spells. <br><br>Murder, on the other hand, is a different story. Lightly based off of the animation "Attack on Titan," the idea here is that the act itself of murdering someone, the draining of their life force, is the most potent fuel for magic. This drains the spiritual energy of that individual, and then adds it to your own spiritual reservoir. With enough murders, you can perform magic that most cannot do. Mass telekinesis, speed, strength, regenerative healing, elemental control, etc. <br><br>This concept is important to the story as it not only answers the question of "why is magic so important," but it also answers "why is murder wrong." Magic is so important because it is the unsung driving force behind everything in society. It is how most cities are protected and how most food is made. Most people won't notice it, or they will think that it is the result of something else, but magic is present in the world just like the air in your lungs. Magic makes up most of the "surgeons" in the world. Magic is how most of the food is produced. Magic is how most cities are protected. The reason magic can't be known to the public is that the average person doesn't have enough spiritual energy to perform basic spells. The average magic user must murder a person every 2 weeks or so in order to keep their magic working. If magic was revealed, people would be frightened, because they don't have the magic to protect themselves. Therefor, magic is kept in the dark, and the people who are magically adept are revered by their dark societies. They are the ones who protect and feed society, at the cost of innocent lives. <br><br>**My question is...**<br><br>How would this magic fuel effect society? What type of societies would be created in a world like this? How would the people who have this magic be treated? Would the people be fearful of them, reverent, or hateful? How would the non-magically adept be treated by them? <br><br>My story revolves around the "moral" societies, the ones that keep magic hidden and out of sight. They see themselves as above the law because they must commit murder to do what they do. Most see the non-magically adept as inferior to them, and a sacrifice that must be made for magic to continue. They find their "moral" standards in how they choose to kill and who they kill.<br><br>What other ways do you see magic like this being depicted in a story, or how do you see it being depicted in this story?