Void Walker

Rogues that choose this archetype often come from nothing. Having little to lose and all to gain; they are the ultimate daredevils. Void Walkers possess a unique relationship to the Void. It is a part of them, as they are an extension of it. This connection grants them strength, speed, and otherworldly skills.

Drawing power from the Void, Void Walkers gain the ability to cast spells, using Charisma as the spellcasting modifier.

Coat of Nebulas

Starting at 3rd level, you gain advantage when taking the Hide action in dim light or darkness.

Your connection to the Void allows you to use the darkness to your advantage. While you are in dim light or darkness, you may use your reaction to impose a disadvantage to an attack that targets you, as long as you are able to see or hear the attacker, and are not feared/charmed/incapacitated. You may use this feature a number of times equal to your Charisma modifier. You regain all expended uses during a short or long rest. 

In addition, when hiding in dim light or darkness, you can invoke the shadows from the Void to conceal your form, allowing you to become invisible to all nonmagical sight. You become visible again when you move or take any actions. 

Void Magic

When you reach 3rd level, you gain the ability to cast spells. 
Cantrips. You learn two cantrips: Chill Touch and another cantrip of your choice from the warlock spell list. You learn another warlock cantrip of your choice at 13th level. 

Void Step

Starting at 9th level, you learn the spells misty step and blink, both at the lowest level. Your spellcasting ability modifiers for these spells are your charisma modifier. You may use each spell a number of times equal to  your charisma modifier. You regain all expended uses during a long rest.

Additionally, on your first turn at the beginning of each combat encounter,  you may move up to 10 feet extra to your normal movement speed. If you do, you may make an extra weapon attack as a free action at a target within range.

Echo of the Void

By 13th level, you are deeply connected to the void. You learn the spell Silence, at lowest level, and gain the ability to cast it once per short rest, as an action or a reaction.

Additionally, you may project your voice to appear as though it's coming from any location in dim lighting or darkness within 60 feet of you that you can see, as long as you aren't feared, charmed, or incapacitated. 

Void of Space

When you reach 17th level, your bond with the Void is deeply set.  It grants you the ability to walk through the void of space.  After each weapon attack you make, you may gain use of a free action to teleport up to 30 feet in any direction to an unoccupied space without provoking an opportunity attack. 

Additionally, whenever you successfully avoid an attack,  you may use your reaction to teleport up to 10 feet in any direction within your line of sight, without provoking an attack of opportunity.