Satsui No Hado

it's described as taking the spirit to kill the opponent to the extreme, and transforms it into a physical power.A form of fighting made towards the purpose to kill, specifically Ansatsuken,(School of the Assassination Fist) come to have their repertoires and teachings intertwined with its power upon their founding, and their techniques ultimately hold the potential to develop the Satsui no Hado due to its originating intention. It is said to be a power rooted in the darker natural basis of the human instinct, including competition, survival, to trample on, impose, and thrive over opposition, and the manifestation of destruction borne out of conflict and fighting.

For the people who do succeed in harnessing it, they become extremely powerful, but at the cost of losing their humanity and compassion; they develop a cold, negative outlook on life, a nihilistic detachment from themselves, as well as other people, and develop an obsessive, dark, murderous, and even suicidal desire to fight. The darker the influence, the more drastic your appearance, actions and morality will vere towards those of an evil nature to a point you will likely fully align your heart with violence and death.

 

Appearance

1. a person's eyes will glow red

2.  their teeth will extend into sharp fangs

3.  their skin darkens over time.

4. Their hair also turns red,

5. their nails grow into claws.

6. The voice of the user will also become deeper to the point of gaining an echo effect. 

Manchineel Mentality

At the cost of losing their humanity and compassion; users develop a cold, negative outlook on life, a nihilistic detachment from themselves, as well as other people, and develop an obsessive, dark, murderous, and even suicidal desire to fight. That said, their minds are poisoned with the thoughts of violence yet to come and the delights of deadly combat. Your rage is a constant but not your driving force, it is your thirst for violence and may be consumed in the pursuit for a true rival or even to prove your superiority. Any and all forms of competition excite you and the lack of it will drive you mad and starved for battle.

Ansatsuken-shoto

The assassination fist is the school of fighting that sustains and demolishes the users life. Whenever you hit a creature with one of the attacks granted by your Flurry of Blows, you can impose one of the following effects on that target: 

Tatsumaki Zankukyaku - Hurricane Scythe kick -  The practitioner jumps and, while in the air, rotates their legs, kicking the opponent 1~3 times with lightning and burning passion

Messatsu Gorasen - A more powerful version of the Tatsumaki Zankuyaku, the Messatsu Gou Rasen rises vertically, pulling a struck opponent into a "vacuum"

If performed in midair as the Messatsu Gou Senpuu, it inflicts much more damage, and the user floats a little during the attack before finally rising up like with the grounded variation.

Goshoryuken - Target must succeed on a Constitution saving throw or be hit by the user's strike to the foes chest and jumps from a standing position. The next attack against the target has +10 to its damage roll.

Goshoha - It must succeed on a Dexterity saving throw or be flipped over the user's shoulder prone likely with a broken bone

Tenmakujinkyaku - The user jumps, landing in a diagonal-fall with a strong kick that inflicts high damage with the outer metatarsal portion of their one of their feet. The target must make a Strength saving throw. If the attack is successful, they can follow up with any other attack, making this a good combo starter.

 Ashura Senku - the user widens their stance, glows red, then lifts one knee and "glides" along the ground to another location with their eyes aglow. They cannot be hit while gliding, essentially making the move a teleport or a phasing though an area through pure will or  forcing the world to lag behind their frightening speed

 

Gohadoken

Starting when you choose this tradition at 3rd level, you can hurl hellish bolts visible of Rage Energy.

You gain this new attack option that can be quickly discharged or supercharged but held to charge for 1 round at arange of up to 35 ft. You are proficient with it, and you may add your Dexterity modifier to its attack and damage rolls. Its damage is force, and its damage die is a 1d4 per character class level

When you gain the Extra Attack feature, this special attack can be used as a bonus action

Kyoi no Hado (Furious Meditation)

The Power of nothingness. It is the complete opposite of the Satsui no Hado. As such, it can only be used by a person of pure mind, compassion, mercy and peace. Such a person must have embraced the peaceful and spiritual aspect of the art to their fullest extent. Just like the Satsui no Hado, it makes a person unbelievably powerful, granting invincibility (spiritually and physically) to many attacks, as well as sealing off evil power and making the user a stronger fighter. Early in these days of their journey, the user attempts to put down their thirst for violent urges to achieve this so called greater power but often find themselves further in anger. This act of furious meditation helps you pass the time and build your rage as you hone in on a target, the user seems to have a sixth sense as to where battle, conflict and strong fighters you've met.

Abilities

A user of the Satsui no Hado gains immense strength(+7 to hit), as well as the ability to both sense and absorb other sources of power to make themselves stronger. They also gain abilities such as telekinesis, flight, and can also potentially influence the emergence of the Satsui no Hado in others. Once an individual has tapped into the Satsui no Hado within them, it can be very difficult to resist conflict and conquest. 

Shun Goku Satsu

The final move of the Ansatsukan.

The raging demon-The user glides towards the opponent and grabs them and release a series of progressively faster teleport punches targeting vital weak spots located throughout the body, solidifying that the technique utterly destroys the opponent's body until it progressively forces your opponent to feel themselves die 1000 deaths by using the weight of their sins against them.While the executed attack is a brutal onslaught of merciless fury, the basis of the attack is said to be linked to karmic forces drawn from the influence of the Satsui no Hado, channeling an infernal punishment in which the weight of sins and evil the victim has committed attacks their soul. While immensely powerful, this attack cannot work on artificial life forms or people who lack souls. There is only one method known to perfectly counter this attack that some characters have survived its wrath, being mastered the Power of Emptiness. The target must make a DEx save of 8(Good) 10 (Nuetral) 12 (Evil) to dodge and a CON NAT 20 if save fails. Damage is up to DM discretion.

 

Ten no akuma

Kagenaru Mono "The Shadowed One are the entity personifications of the hado's influence in users minds. The influence inside clawing for battle. In any instance where the hado becomes merged with the user they create a new form, free from the burden of their humanity much less morality and their rationality for anything but battle.

Consult DM for appearance and abilities.