Black Devil Slayer Magic (Dreyar)

Black Devil Slayer Magic (黒の滅悪魔法, Kuro no Metsuaku Mahō) is a Lost Caster Magic and a form of Devil Slayer Magic which employs the use of all forms of shadows and darkness. User of this magic are given the ability to slay devils and thus are deemed Exorcist Mages (悪魔祓いの魔導士, Akumaharai no Madōshi). The only known users of this magic are Zadok Mattaniah and his grandson, Areli Mattaniah, whom he passed the powerful magic down to.

Description
Black Devil Slayer Magic, like all of it's kind, must be learned through a Book of Zeref. By assimilating a harmless type of Magical Barrier Particles into their own body and Magic Origin through the instructions given in the Book of Zeref, the user gains the ability of a Devil Slayer. They will gain the properties of their chosen element, in this case shadows, as well as a slightly, nearly unnoticeable, dark aura about them. Additionally, they are given the ability to consume external sources of darkness to recover strength, including the shadows of both Dragon and God Slayers. They cannot however consume darkness they have generated from their own bodies, or darkness that has been generated from a darkness-related Curse.

Once a user has become proficient in wielding this magic of theirs, they can utilize it in a number of different of different methods, such as infusing weapons in their possession with darkness to enhance their destructive capabilities, or even create their own signature weapon out of pure darkness. With this magic they have complete dominance over shadows, and can even sink down into a shadow if the situation calls for it. While this magic is capable of dealing considerable damage to mages, it's initial purpose to slay devils proves to be it's most effective use, as Etherious and other demons' bodies are more susceptible to damage from this form of magic.

Basic Spells
Black Devil's Rage (黒滅悪怒り, Kuro Metsuaku Ikari):

Black Devil's Tainted Palms (黒滅悪腐肉掌紋, Kuro Metsuaku Funiku Shoumon):

Black Devil's Scimitar (黒滅悪罰当り偃月刀, Kuro Metsuaku Engetsutou):