Over Soul

Over Soul (オーバーソウル, "Ōbā souru"), or simply O.S., represents the ultimate form of Furyoku manipulation for a Shaman.

About
An Over Soul is the metaphysical construct of an apparition using a shaman's Furyoku and a medium to gain corporeal properties. An Over Soul 'actualizes' the knowledge and memories of an apparition and allows their memories to manifest essentially as magical powers. They are composed entirely of Furyoku and being so, there is no actual matter. An Over Soul can only be damaged by another, this renders all form of conventional weaponry useless, as there is no matter to interact with. While any spirit can be molded into an Over Soul, their attributes depend solely upon the spirit's ego - or identity. Depending on its ego, the ghost can be molded by the shaman into any shape or form the shaman desires, enabling the direct display of its abilities to protect the shaman.

Human ghosts usually make poor choices for an Over Soul due to their egos but can evolve over time into higher spirits - spirits whose souls have been refined over hundreds of years and have attained their purest form. While the exact design of an Over Soul depends entirely on the shaman's imagination, it's also important that the shaman uses a medium which best symbolizes the spirit's abilities, such as a katana for Amidamaru who is a samurai.

In regards to strength and integrity, an Over Soul's durability is proportionate the amount of Furyoku charged as well as the shaman's level of concentration. It is important for the shaman to keep in mind that although the mass of an Over Soul remains constant, Furyoku is consumed anytime it is used to create matter, like ice, which consumes Furyoku in itself. Furyoku is only consumed when the "body" of the Over Soul is compromised. At this juncture, the Over Soul is charged with the proportionate amount of Furyoku necessary to maintain its integrity, depending on the degree of damage sustained. If an Over Soul absorbs enough damage, it breaks and dissolves along with all Furyoku used in its creation. Therefore, a shaman must consider how much Furyoku to charge their Over Soul with during each engagement.

The sizes and shapes of certain character's O.S. often change since their introductions, some without any explanation. This could be attributed to the mental imagery a shaman uses to envision the form, size, and ability of the Over Soul. Yoh's Spirit of Sword, for instance, has changed throughout the series since being introduced in volume 15 of the manga, with a defined blade and the inclusion of a large hilt.

Spirits themselves have three sub-categories:
 * Ghost-type: Normal-class spirit ally
 * Seirei-type: Sacred-class spirit ally
 * Kami-type: God-class spirit ally

Types of Over Souls
Generally speaking, O.S. can be divided into three categories: Spirit-types, Weapon-types, and Armor-types. Strictly speaking in terms of practicality, the classification of an O.S. doesn't necessarily determine its effectiveness in live combat, but the higher the quality of the O.S. determines its range of abilities and maintenance, making the overall effectiveness of any O.S. largely based on the shaman's individual talent.

Spirit-type Over Soul
Spirit-type O.S. usually manifests an apparition corporeally in such a manner as to fully utilize its unique abilities. (ie. O.S. Bason, O.S. Kororo-Snowboard).

Weapon-type Over Soul
Weapon-type O.S. manifests an apparition in its purest form, usually as a supernatural armament (ie. O.S. Spirit of Sword, O.S. Kororo-Ikupasuy, O.S. Super Bushin), usually to compliment the shaman's personal fighting style. Weapon-types are incredibly versatile and are made possible once an apparition ascends to the Seirei-class.

Armor-type Over Soul
Armor-type O.S. is the most efficient type. Armor-types represent the pinnacle of O.S. magic and are the most practical type of O.S. because of their resilient, highly dense Furyoku construction. This method makes them equally formidable in terms of raw power.

Unity-type Oversoul/Over Soul Merge
Unity-type O.S. is very difficult to pull off since both the ghost and the shaman must be in sync the entire time the O.S. is used. The Shaman makes sure that they and the ghosts are one and the same. The advantage is that the ghost is fully used in the battle and allows for a direct use of all abilities of both shaman and ghost. The only example of this is Chocolove McDonell and Mic the Jaguar.