Dreadskull (Polished)

Dreadskulls are often individuals who have formed a symbiotic relationship with a vengeful spirit.
The spirit uses the host to further it's own ends, while the host gains a suite of horrifying powers. They appear as normal mortals, made of flesh and bone, but in an instant, they can transform into a nightmarish creature that strikes fear into the hearts of even the bravest warriors.

Dreadful Form

When you choose this archetype at 3rd level, you walk the line between the living and the dead. As a bonus action, you may enter Dread Form. Dreadful Form is similar to concentration, and when hit you will need to make a Charisma saving throw to remain in the form. While in this form, you gain resistance to necrotic damage and don't need air to breathe. Dread Form lasts for 1 minute, and can be used once per short rest. Additionally, when in Dreadful Form, can deal an additional 1d6 necrotic damage per each attack. With every new feature gained, this necrotic damage increases in 1 dice size. (1d6->1d8->1d10->1d12)

Gaze of Terror

At 3rd level, your ghostly visage strikes fear into your mortal enemies. While in dread form you can use a bonus action to force a creature you can see within 60ft to make a Wisdom saving throw (DC 8 + Your proficiency modifier + your charisma modifier). On a failed save, they are frightened of you for 1 minute. You may freely sneak attack the target creature on a successful hit if they are frightened by you. A frightened creature can make the save against Gaze of Terror at the end of it's turn until it succeeds. After succeeding the save, the creature is immune to this feature for the next hour. You can use this feature an amount of times equal to your Charisma modifier (Minimum 1).

Ethereal Stalker

At 9th level, you learn to borrow your bound spirit's ghastly form. While in Dread Form, when you frighten a creature with Gaze of Terror, they are plagued with visions and illusions of you all around them, closing in for a kill, stalking, waiting to strike. The target creature will have disadvantage on Perception(Wisdom) and Investigation(Intelligence) checks while frightened. Once per use of Dread Form, you may blink to a target who is frightened by Gaze of Terror and strike at them with a singular attack, rolling with advantage. This feature is limited to 120 ft.

Fear Itself

At 13th level, you become an avatar of fear. When you enter Dread Form, you gain Temp HP equal to your Rogue Level + your Charisma modifier, as well as any class features that have a limited amount of uses refresh one use. The Temp HP goes away when Dread Form ends. Whenever you deal Sneak Attack damage to a creature that is frightened of you, deal an extra 3d6 psychic damage.
Additionally, your mastery of terror grants you immunity to the Frightened effect. You also gain Advantage on Intimidation(Charisma) checks.

Terrifying Execution

At 17th level, the fear of death you instill in others becomes a literal weapon for you. Whenever you reduce a creature that is frightened of you to 0 hit points with a weapon attack, you can use your Gaze of Terror as a reaction on a different creature you can see within 60ft of you. On a failure, in addition to the regular effects of Gaze of Terror, roll your sneak attack dice. Deal half the damage you rolled as Psychic damage to the targeted creature.
This use of Gaze of Terror does not count against your total uses.