Ruined King

This Fighter Subclass is meant to feel like playing Viego from League of Legends.

Blade of the Ruined King

Beginning when you choose this archetype at 3rd level:
Your body is infused with a Black Mist. It feels alive and it's goal is to help you survive.

[Mark of the Black Mist] - When you hit with a normal melee attack on a target marked by your Black Mist, the mark bursts and returns to you. The target takes an extra 1d6 necrotic damage, removing the mark from them, and you heal that many hit points. At level 7, the damage increases to 2d6. At level 15, the damage increases to 3d6. At level 18, the damage increases to 4d6.
If a marked creature is ever more than 120 feet away from you or 1 minute has passed, the mark dissipates and the mist is returned to you.

[Blade of the Ruined King] - When you take the Attack action on your turn, you can forgo one of your attacks to thrust your Black Mist with your sword in a 20 foot line. Each enemy in the line is marked with your Black Mist and makes a dexterity saving throw DC 8 + Proficiency Bonus + Strength or Dexterity Modifier (your choice). On a failure, they take 1d8 damage, and half as much on a success. The damage goes up to 2d8 at level 10. And 3d8 at level 18.

Your Black Mist is constantly circulating around your body.
[Unarmored Defense] (10 + Dexterity Modifier + Constitution Modifier)

Spectral Maw

Starting at 7th level, as an action, You can become one with your shadows and dash up to 15 feet in any single direction and using that momentum, you shoot your Black Mist out 30 feet as a ranged attack that does 2d10 damage and marks a target with your Black Mist. The dash does not provoke opportunity attacks Upon hitting this target, they must succeed a Wisdom saving throw (8 + Proficiency Modifier + Strength Modifier) or be stunned until the beginning of your next turn.
Your movement speed is increased by 10 feet

Harrowed Path

As a bonus action, you may have your Black Mist shroud you and invigorate you for 30 seconds. While Harrowed Path is active, your movement speed is increased by 20 and you gain an extra action each turn that can only be used for a single weapon attack. Creatures can only see you clearly if they are within 40 feet of you.
You may use this ability as many times as half of your proficiency modifier rounded down, resetting on a long rest.

Heartbreaker

You may teleport within your  movement speed range and slam your Black Mist out onto a 20 foot radius around you. Each creature you choose in the radius is marked with your Black Mist and makes a Dexterity save. On a failure, they take 1d10 necrotic damage and their movement speed is halved for one round. On a success they take half damage.
Once you use this feature, you must finish a short or long rest before you can use it again.

You also gain a reach of 10 feet to a marked target.

Sovereign’s Domination

When a creature that you have damaged dies, as a bonus action, you may teleport to their corpse and allow your black mist to copy their soul and polymorph into a basic Spectral form of that creature with half of the target's maximum hit points. While transformed, your Intelligence, Wisdom and Charisma become either yours or the target's (whichever is higher).
You may use this feature 3 times per long rest.