Il-Nyarzuthoph

Il-Nyarzuthoph (, Iru Niyaruzūtōto; lit. "Wicked Eye Inception of the Formless Demonic God") is an eldritch ability that's existed since time memorable, achieved by those who've, in the words of its users, "traversed and fully understood the very depths of the magical abyss"; to this extent, one can consider it to be a "form of understanding" — though involving territories outlawed by the laws of the magical world. Since it usually synonymous with Demons, it's considered to be a form of the Black Arts.

A Forbidden Magic, it's considered to be a Subspecies Magic of Eye Magic — as it works in the same way; interestingly enough, despite it being used by extremely powerful Dark Mages and Demons alike, such an ability is also exhibited in the forms of certain Devil Synchronization users. This is rather typical given that such a form is basically demonic in composition, an ironic twist for Exorcist Mages — their purpose is to purify such entities. To this extent, it's also considered to be a supplementary of Devil Slayer Magic. Such mages often refer to this magic as the Evil Eye (邪眼, Jagan), alluding to its sinister nature.

Overview
"Before this "evil eye", all things will be shrouded in darkness, corrupted under the weight of my power. Before it, nothing can be hidden from me~!"

- A Dark Mage subtly alluding to the powers of the evil third eye.





Trivia

 * The name of this magic is based on two sources: Il-Illah, the formless god of Alma-Torran from the series, Magi, and Nyarlathotep, the primordial demonic entity of chaos and the grandfather of the infamous Old One, Cthulhu from the Cthulu Mythos of the eldritch horror author, H.P. Lovecraft; the overall capabilities are leaning towards the latter.
 * To be honest, such a third-eye was also based on the ones seen in Djinn Equip from the aforementioned anime/manga series, the author theorizing that such a trait is related to the Magi itself.


 * To an extent, this is also based on Hiei and his infamous Jagan Eye seen in his demonic form from the series, YuYu Hakusho.
 * While the power of the is something seen in many religious beliefs and integrated into various anime/manga because of its representation, the connotation in this case is inverted — making it more demonic than the norm. In this case, the use of the third eye is based off of one of the various forms of  worshipped by the.