NightStalker

The NightStalker is one who has chosen the life shy of the light, preferring to stalk its targets in the dark and strike when they least expect it. You have honed your skills to be best in darker areas of the world, NightStalkers think of themselves as the ultimate ambush predator who seek to eliminate their targets before they even know they were there.

By taking on the mantle of a Nightstalker, the rogue is taken in and kept in the darkest rooms of a underground jail until they develop both a taste for the dark and a keen sense of themselves whilst in the dark.

Raised in Shadow

Starting at level 3, From your vigorous training in the pitch black you have come to perceive things around you without the need to directly see them. In darkened or obscured areas you gain Blind-sight and are able to perceive enemies that a normal rogue could not.
Additionally you may cast Fog Cloud without any components, You may do this a number of times equal to Proficiency bonus +1. You must complete a short/long rest to regain your Fog Cloud uses.
At 7th Level you may cast Darkness Instead of Fog Cloud if you choose.

The Dark Is Your Ally

At level 9, You find yourself to have improved your natural abilities while not being seen. While you are obscured, in stealth or in less than normal light (dim or lower) you gain 10ft Movement speed, Gain advantage on all Dexterity and Strength ability checks and gain advantage on initiative if you start combat in stealth or obscured from view.
At level 13, your movement speed bonus is doubled as you become even more attune to the dark.

From the Dark you Strike

Starting at level 13, you begin to strike out at your targets that move too close to the dark, lashing out upon their eyes or "seeing appendage". When someone moves past your melee range whilst obscured, you can as a Reaction make a special attack on them, The target takes your sneak attack damage and is considered blinded for 1d4 rounds.

At level 17 the target is blinded for the maximum 4 rounds.

Night Terror

Starting at level 17, You become viewed as a nightmarish devil by those who have perceived you in the dark, When a creature becomes aware of your presence coming out of or in Darkened/obscured areas, they must succeed on a Wisdom saving throw, DC equal to your Rogue level or else they become frightened, They may make a saving throw at the end of each of their turns to end the Fright. If the target loses sight of you whilst frightened and affected by this feature again, they are paralyzed from the sheer nightmare of your presence and must make the saving throw at the end of its turn at disadvantage. If the creature is Paralyzed for 2 turns, it succumbs to the Night Terrors and takes 12D12 psychic damage.