Yomi-no-kuni

Yomi-no-kuni (黄泉の国腐魔方陣 (ヨーミ·ノウ·クニ), Yōmi-nō-kunī; Japanese for "Land of the Yellow Springs' Tainted Magical Seals"), simply referred to as Yomi (黄泉, lit. "Path to the Underworld") by most individuals, is an extremely powerful & versatile form of the Black Arts — making use of the basic principles of Formula & combining it with the former to bring about much devastation to both the target and the user's surroundings; this makes it a Caster Magic. It's considered to be a darker variation of Amaterasu, the two sharing many similarities with one another. It's also considered as a unique branch of Darkness Magic — some of the art form's spells utilizing the element in various ways, thus can also be dubbed as a form of Subspecies Magic.

It's unknown when this magic was created, but it's said that it was during the waning days of the magical world — where magic was still evolving. It had many practitioners, most of whom were Dark Mages. In this retrospect, it's seen as one of the oldest forms of magic to-date. A record shows that this magic was used in various battles, decimating armies, obliterating landscapes, and bringing about victory to whichever side that wielded in the most effective manner; this garnered it the title of "The Black Ship Magic" (黒船の魔法, Kurofune no Mahō). However, due to the magic being later abused for nefarious purposes, it was labelled as forbidden by the then-Magic Council, and its practitioners hunted down & exterminated. In a ditch effort to preserve it secrets, it was recorded in ancient scrolls, tomes, & books and sealed away in various locations so that no individual would easily find it; this trait is commonly seen about many Black Arts forms.

It's unknown how many users of this form still exist, but the number is very low — only some are able to get their hands on the information pertaining to it.

Overview
"Just by arranging the seals of this magic in a different order, I can bring about various calamities. Explosions, corrosion, extreme manipulation of the weather, quakes of various magnitudes. Even the manipulation of darkness on a much larger level is not a mere pipe dream. This magic is everything a Dark Mage, such as myself, would want and even more! With it.... I can possibly conquer a country, nay, the world even! HAHAHAHAHAHAHAHAHAHAHAHAHAHAHA~!"

- A maniacal, power-crazed Dark Mage explaining the destructive capabilities of this magic when used in "certain" ways.

Spells
There currently doesn't seem to be many spells for this form of magic, as much of the information pertaining to it has either been forever lost or hasn't been found as yet. However, such a lack is covered by its overall destructive & cataclysmic power — something that's unique, even amongst the Black Arts. It's known that current practitioners are making an effort to come up with their own spells for this Black Arts form in order to expand on the devastating possibilities that this form contains, substituting it with the ones that haven't been found and/or lost.

Unlike Amaterasu, this magic follows a unique naming system — it being dubbed as "Pole Star's Tainted Formula" (妙見の腐式, Myoken no Fushiki).

Trivia

 * This form is a Black Arts-variant of the Amaterasu and other magics revolving around the use of spell formulas. The author wanted to experiment whether it's possible to create such a thing without it seeming too overpowered while giving it the ability to decimate the opposition with ease (if used correctly).


 * It's known that this magic shares some peculiar relationship with Izanagi, Susanoo, & Kagutsuchi — though one that's considered to be minuscule.