It is a form of Ancient Spell that allows its users to use a specific element to slay Demons. It also lets the user eat their respective element to replenish strength and become immune to its effects like other types of Slayers. It has also been suggested that Devil Slayer Magic is a very fickle Magic, and that learning it too quickly and making use of its properties in rapid succession can have adverse effects on the user, causing them to "demonize" becoming afflicted with black markings that spread across their entire body, covering up to nearly half of the user as well as changing the color of the eye on the afflicted side of their body at it's peak; although those who master this Magic are able to summon these markings at will, allowing them to become immune (to a limited degree) to the effects of Curses (including the "Ultimate Curse" Memento Mori, which is supposed to completely annihilate whatever it touches.) It has been specifically mentioned that the souls of those who hunt Demons start to become "tainted", leading the users of this Magic to progressively lose their sanity, of which can incite them to make irrational decisions. This Magic also allows its users to obtain information about a Demon by just observing it for a second. Also, as function of being an exorcist, Devil Slayers have the ability to kill and/or exorcise demonic power by exerting their Magic Power upon the target, in other using the "demon" side of their Magic, given it being the true purpose of the Magic.