Martial Archetype: Inner Demon
You have a demon trapped within you, it might be a Oni linked to your soul, or the shard of a demonic creature from the abyss. You have learned to use the demon to empower yourself and channel it's energy in combat.
Unleash the demon
When you reach 3rd level, you can unleash your inner demon, and wreak havoc, or stay in your normal form and build up your wrath.
You have two forms, your normal form and your demon form which is called "Wrath form". On your turn you can use a bonus action to switch to the other form.
When you hit a creature, you will gain some energy, when you hit a creature in your normal form you will gain 1 wrath. If 1 minute goes by where you haven't gained any wrath, you lose it all, and you can maximum have 10 of wrath.
Deadly Moves
You have a list of moves that you can unleash in your forms, you will find a list of moves at the end of this subclass. The moves can only be made in the form they belong to.
Starting at level 3, you can pick 3 moves that you know, whenever you hit a creature with a melee attack while in your wrath form, you can choose to use a move. You can't use the same move twice in a turn.
You learn one additional move of your choice at 5th, 7th, 10th, 13th, 15,th and 17th level. Each time you learn new move, you can also replace one move you know with a different one.
Saving Throws, some of your maneuvers require your target to make a saving throw to resist the maneuver's effects. The saving throw DC is calculated as follows:
Move save DC = 8 + your proficiency bonus + your Strength or Dexterity modifier (your choice)
Face of Friend and Foe
At 7th level you can both use your calmness and your anger when trying to make a statement to another person. When you are in your normal Form you have advantage on Charisma (persuasion) checks, and when you are in your Wrath Form you have advantage on Charisma (intimidation) checks.
Surge of Power
When you reach 10th level you have learned to gain energy when you feel the rush of battle. Whenever you use your Action Surge feature you gain 3 Wrath
Energy Spike
at 15th Level you can strike an enemy hard and draw energy as their life essence leave the body. Whenever you hit an enemy with a critical hit or reduce another creature to 0 Hit Points you gain 3 Wrath from the attack instead of 1, if you are in your wrath form you gain 2 wrath.
Ultimate Move
When you reach 18th level you have learned the ultimate move that requires you and your demon to work together and uses both your focus and wrath.
Massive Nerve Strike (Cost: 7)
The Target takes an additional 12d8 Force damage and must succeed a Constitution saving throw or be Paralyzed until the end of your next turn.
Once you have used this move you must finish a short or long rest before you can do so again.

Wrath Moves
These moves expend Wrath and can only be used while in your wrath form.
Switching Dance (Cost: 1)
The hit creature must make a Dexterity Saving Throw, on a fail you and the creature switch place. If the creature is Large or bigger it has advantage on the save.
Demon Rush (Cost: 1)
You gain an additional 20 feet movement until the start of your next turn.
Leg Swipe (Cost: 2)
The creature hit must make a strength saving throw or be knocked prone, if the creature is Huge or larger it has advantage.
Overwhelming Grasp (Cost: 2)
You can immediately make a grapple attack against the creature you just hit.
Distracting Maneuver (Cost 2)
The next creature other than you, that makes an attack against the hit creature will have advantage on the attack roll.
Defensive Stance (Cost: 2)
You gain +2 to your Armor Class until the start of your next turn.
Credit
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Inspiring Performance (Cost: 3)
You choose another creature within 30 feet of you, that creature gain Temporary Hit Point equal to half your fighter level.
Horrific Strike (Cost: 3)
The hit creature must make a Wisdom Saving Throw or become frightened until the end of your next turn.
Wide Strike (Cost: 3)
You can immediately make another weapon attack with the same weapon, against another creature within 5 feet of the original target.
Teaching Strike (Cost: 3)
You choose another creature within 30 feet of you, that creature can immediately use its reaction to make a weapon attack.
Demonic Skin (Cost: 1-10)
You gain Temporary Hit Points equal to 1d6 for every point of wrath spent on this move, the Temporary Hit Points last for 1 minute.
Fiery Edge (Cost: 1-10)
You deal an additional 1d6 for ever point of Wrath spent on this move as fire damage on the hit.
