I've recently come to acquire a spare soul and instead of just leaving it to spend eternity in the King of Hell, I thought it would be great to implement it in my fights as summon/jutsu.
Name: Pending
Summary: Controlled via the Outer Path, a ravenous and crazed spirit walks the battlefield, desiring physical energy (身体エネルギー, shintai enerugī). It will relentlessly attack those the user directs it towards, wanting to consume their energy. However without a body it cannot sustain it and becomes hungry again after leaving the victim a wasted corpse.
Description/Abilities: This jutsu involves the manipulation of a soul as personal summon. The modified soul is immortal and cannot be permanently destroyed or damaged. It is immune to most attacks except those that block the spiritual or is mostly Yin based (ex. Nara Clan techniques), but as for other jutsu it simply phases right through. If it comes in contact with a creature, person, or thing that has a soul of its own, the spirit can inhabit it and begin feasting on their physical energy. This begins to wear them down, draining them of their strength to the point their bodies are in an emaciated state, possibly destroying years of training, making their stamina, strength, speed, and reaction speed, almost non-existent until their body shuts down due to organ failures.
Advantages: The spirit is immortal and is difficult to sense. The soul is virtually immune to most jutsu. It can merge with objects to keep it hidden from sight or simply phase through most physical objects. Only needs slight contact for it to take residence in a host.
Weaknesses: Fuinjutsu that traps objects/people inside. Most Yin related chakra techniques which bind or harm, keeping it incapacitated (depending on the affect and scale of the jutsu) for a few turns or indefinitely for the remainder of the battle. It cannot cause any harm to the physical body expect through it's effect (ex. It cannot punch/kick/ or use a jutsu on you) and it can still be sensed while overlapping or indwelling objects or people. Attacks the block/harm the soul (Human Path, Shinra Tensei, Yata Mirror etc.). Immense willpower can also cast out the soul (but with every time it dwells inside, the effects remain the same as if it stayed) The effects of the soul wear off after an hour.
The effects are as followed:
First Turn Contact/Indwelling: The victim finds themselves unable to sustain body vitalizing or enhancing techniques (Chakra Release Armors, Bijuu Cloaks, Gates etc.) for no more than than 2 Turns before reverting back to their normal state.
Second Turn Contact/Indwelling: The victim begins to decline in physical strength, speed, agility, and reaction speed by 25% percent.
Third Turn Contact/Indwelling: The victim is at half strength, their bodies shrink in muscle mass and fat significantly, making it a challenge to move as they begin wasting away. They become sluggish, unable to sustain vitalizing techniques for but a turn, but they are less effective than they were before (Jinchuriki don't benefit from the pull power of their Bijuu Cloaks, Gate users don't gain as much strength and speed, etc).
Fourth Turn Contact/Indwelling: The victim is completely emaciated, their muscles and fat virtually wasted away, unable to move a finger. Body enhancing techniques are completely neutralized. With the extreme imbalance of spiritual energy flowing through them, they feel something akin to starvation. Their reaction speed is slowed incredibly and organs begin to fail.
Fifth Turn Contact/Indwelling: Death. Muscles are completely disintegrated, all organs fail, and what remains is a shriveled corpse.
I will like thoughts, opinions to improve, whether you like the jutsu or not, etc etc.