Eidolon Devil Slayer Magic

Eidolon Demon Slayer Magic (化身滅鬼魔法, Keshin Metsuoni Maho) is a form of Lost Magic used by Demon Slayers.

Description
Eidolon Demon Slayer Magic (化身滅鬼魔法, Keshin Metsuoni Maho) is a branch of Lost Magic which allows its users to transform the physiology of their body into those of a demon. Eidolon however is a unique type, since it does not utilize a specific elemental typically found in Demon Slayer Magic, instead the caster acquires the powers of a demon through what is known as the covenant, an unholy contract binding the soul of the caster to the Demon. By invoking an incantation which serves as a summoning he can allow a portion of the Demons power to manifest through him, making this style of Demon Slayer Magic a Holder Type. The caster acts as a vessel for the Demons power and takes on many of its physical and psychological characteristics.

Unlike other Slayer Magic, where the style is generally taught by the creature in question to the caster, Demon Slayer Magic instead uses the caster as an avatar or a vessel for the Demons power. Furthermore with every use of this magic, the caster's physiology begins to change, as the physical characters of their demon begin to manifest along with augmented physical abilities, and magic in their base human form. Furthermore the type of magical enhancements a Demon Slayer obtains depends wholly on the Demon they have made a contract with. Therefore Demons with a strong affinity for a specific element will bestow that same affinity and associated abilities to the caster. Ultimately the type of enhancements and abilities bestowed upon the caster are wholly dependent on what powers the Demon in question has.