Spirit Slayer Magic

Spirit Slayer Magic (滅気魔法, Metsuki Mahō) is a Caster-Type Lost Magic used by those trained in hunting and destroying the supernatural; it was created by spirits to hunt down summon spirits such as Celestial Spirits and Familiar Spirits. Spirit Slayer Magic is only recent, because of this, there are very few users.

Description
Spirit Slayer Magic is a form of Lost Magic in which the caster is able to attain the abilities of a spirit of any type, using a specific element as their type. The certain elemental type of Spirit Slayer Magic can be conjured from the caster's body and be used for various purposes, mainly in combat. Spirit Slayer Magic allows the user to integrate a spirit's magical power with their own. Once it has successfully interlaced, they are given a myriad of abilities. These are mainly produced through the user's own body, but instead of the element being present inside the body, the user's magic shall absorb any trace of that element in the immediate vicinity, and/or use the correct reactions in order to produce the element continuously.

A Spirit Slayer is immune to the effects of their own element, and can consume external sources of their element to replenish their strength. However, a Spirit Slayer cannot consume the element that they produce themselves, and elements must be consumed through the mouth. It is known that certain Spirit Slayers have been able to consume elements other than their own, allowing them to combine both elements inside their bodies and use them to increase their abilities. The classifications of this magic aren't limited to basic elements such as Fire, Water, Earth etc., but are even broader, ranging from phenomenon such as sound waves to abstract elements such as emotions. Spirit Slayer is not solely restricted to elements though, as not only elemental-oriented spirits can teach it; meaning that there are many possibilities for the style, as even unorthodox aspects can be manifested, such as gravity, emotions, and mimicry.

Following the closure of the civil war between Dragons and Humans, along with the reign of Zeref ending, a select few Spirit Mages wished to take over the world with their relatively unknown power being reportedly superior to that of others. To this extent, these mages had begun to conjure spirits themselves using their own magic to do so. Sensing this uneven distribution in supernatural entities, the Celestial Spirit King, along with the ruler of the Familiar Spirits and other spiritual entities began to, in a similar manner to Dragons, teach Humans their ways of combat in order to neutralise this uprising.

Obtaining
In order to obtain the magic of Spirit Slayer Magic, one must forge a contract with spirits of any type, even ghouls hailed as Celestial Spirits which are located within the world of Earth Land—usually one per town. These beings are part of a set created by the 'higher spirits' for the sole purpose of keeping order within Earth Land. First, the foremost requirement is to locate a spirit. Finding one ain't a walk in the park, that's for sure- the user must be knowledgeable in its habitat, its favorite kind of food, and what it wishes to make out of the contract.

Then, upon meeting these creatures, the user is able to separate the yin from yang and insert their own force into the mix, which is fuelled by their willpower- this allows their to connect with the beast and more often than not, the beast and the human will converse mentally, and depending on the course of action, the human will learn a specific branch of Spirit Slayer Magic; it is a mental journey. However, there are two exceptions to mentoring the humans in Spirit Slayer Magic. These two are Ophiucus the thirteenth key, and the Celestial Spirit Key—if any of these two spirits were to attempt to teach a human their magic, they would be unable to accept the force of their magic—those spirits with "Unknown Keys" (for Celestial Spirits) cannot teach their magic.