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.