He is a student at the magisterium, a book series that consists of magic, and if you use to much of an element you can turn into a devoured then the element would replace your soul. But Callum isn't just an ordinary mage in training, he's a makar, which means that he has the ability to control chaos magic and make chaos ridden. Though he doesn't have his own soul, he has Constantine Madden's soul/ The Enemy Of Death. So he can control the chaos ridden that Constantine created. 