Apeiron Knight

"Verto! (ブルト！, Buruto!)"

- The transformation command.

Apeiron Knight (, Apeiron Naito lit. Warrior God Knight Armour) is a Holder Magic and Lost Magic that involves wearing the power of ancient beings of ages past in the form of armour, granting the caster incredible capabilities beyond mortal keen.

Description
Apeiron Knight is somewhat of a unique magic – not because it's simultaneously a Holder Magic, which is a category of magic that requires a magician wielding it to use an external source to produce the effects of the magic, and a Lost Magic, another type of magic that has been obliterated from the history of the world due to their immense power and the sheer gravity of their side effects on the users – however, a Lost-type Holder Magic is pretty rare, considering that Ushi no Koku Mairi is perhaps one of five publicly documented types of magic in the world. No, Apeiron Knight is unique in that it technically comes in three separate parts – the spirit itself, the binding spell, the medium, and the activation thereof.

The first parts of the three that compose Apeiron Knight are the spirits that the caster is capable of manifesting through use of the magic. Referred to as Warrior God Spirits (武神聖霊, Bujin Seirei), these spectral apparitions could be considered similar to other spirits brought into the mortal realm through various forms of Summoning Magic such as Celestial Spirit Magic, but other than them being a lifeform which is different than humans, that's where the similarities end. It's unknown what any designations that these spirits possess, but one thing is for sure – all of them are radically different from one another, and no two spirits are alike. Typically, these spirits take the form of armoured beings with getups that cause them to be highly resiminent of medieval-era knights. These spirits are known to be insurmountably powerful, hence their unofficial designation of "Warrior God Spirits", but one thing that's consistent with all of them is that each "Warrior God Spirit" is noted to be an embodiment of certain concepts which can affect the tide of battle, but normally, they're a crystallization of concepts such as the moon, ice, time and various other things – all of these concepts can be brought into the mortal plane through the arcane, so it can be assumed that in a sense, the "Warrior God Spirits" are embodiments of certain magics. They also wield weaponry that has to do with their element and style of combat.

However, their power is so great that prior to the formation of this magic, the "Warrior God Spirits" were incapable of remaining in the mortal realm for sustained periods of time as their strength had grown to the point that they surpassed almost anything that they fought against. As such, these spectral warriors were forced to be sealed away, and a spell which is a natural part of this magic as well as the building block from which this magic was created was developed – this spell is referred to as "Evinco" (, Ebinko lit. Knight Restraining Seal, Latin for "Enthrall"), and it involves the caster focusing on a potential spirit in its dying moments (or if they're just strong enough), before surging incredible amounts of magical energy outwards as to encompass the potential spirit's entire body, locking down their bodies before inducing a powerful serial of shockwaves infused with their arcane powers that begin to break the potential spirit's existence down into naught but a mass of azurite energy – from here, the next step can be engaged, by sealing them in a Focus, ensuring that its power can be used by anyone wishing to fuse with it as long as the user possesses the qualities deemed as worthy to inherit their power.

The Focus (, Fōkasu lit. Warrior God Activation Treasured Tool) is the medium through which the true might of this magic is capable of being manifested – varying from owner to owner, the Focus takes the form of the object that the spirit was sealed into; typically, the Focus is something that holds great importance to the user who embedded the spirit into the medium, but exceptions can exist; additionally, a spirit is capable of being removed from a Focus and installed within another if a magician is powerful enough. As such, aside from said exceptions, a Focus never changes form even if it has multiple uses – however, in some cases, the spirit alongside the wielder can transform the Focus into a more suitable appearance. While various Focus are utilized to unleash the full might of this magic, a wielder is capable of projecting a portion of the spirit's power from the tool in the form of a single ability. The moment that a hopeful wielder finds a Focus and touches it, their minds will be transported into the Focus, so to speak – inside the tool is a representation of the mental world of the "Warrior God Spirit", filled with recreations and the like of their achievements that people remember it by. From there, the spirit can choose to form a "pact" with whoever they deem worthy and grant them access to their power in a form of armour. These people are known as a "Pact Maker" and are bound with the spirit until death.

Now, everything comes together – through the "Transform" (変身, Henshin) command, the caster is capable of equipping the power of the "Warrior God Spirit" to themselves by releasing the power sealed within the Focus and centering it around their entire body. Erupting from the tool that holds the existence of the "Warrior God Spirit" is a simply inexhaustible torrent of magical energy, the textures of which are dependent on the traits of each spirit – this surge of arcane power rises from the medium for the spirit's power, enveloping the entire existence of the wielder, swirling around their body like a hurricane that causes those whom attempt to gaze upon the sequence to have their eyes forcibly averted due to the density of the energy effectively making the user of this magic impossible to see for the duration of the activation sequence. As the spiraling energies subside, the caster reveals their new form, equipped in armour tailored to the spirit's appearance while wielding their weapon. In this form, the caster has dramatically enhanced physical and magical parameters, with the proficiency of the spirit stacked onto their own power – alongside this, they are capable of performing stronger attacks and spells.

Volticulus
Volticulus (, Borutikurasu lit. Symbol of Power, Latin for "Aspect")

Trivia

 * Apeiron is a Greek word meaning "unlimited","infinite", or "indefinite". This is meant to reference the infinite possibilities of Warrior God Spirits which exist.
 * Interestingly, Apeiron Knight has a unique effect when used by a Celestial Grace user with a compatible Celestial Soul Power.