Base Class: Rogue
You focus your training on the shadows. Empowered by darkness you become a beautiful and terrible weapon.The shadows help you eliminate your foes with deadly efficiency.
Assassinate
Starting at 3rd level, you are at your deadliest when you get the drop on your enemies. You have advantage on attack rolls against any creature that hasn’t taken a turn in the combat yet. In addition, any hit you score against a creature that is surprised is a critical hit.
Dark Desires
When you choose this archetype at 3rd level you also gain the ability to, as a bonus action, create an object of hardened shadow. This construct can take the form of your thieves tools, a dagger or any item your character has seen before. Objects created with this feature fade back to shadow when they are outside of 30 feet from the shadow assassin. The items are distinguishable from normal items as they are completely matte black.
Shadow Step
At 9th level, you gain the ability to step from one shadow into another. When you are in dim light or darkness, as a bonus action you can teleport up to 90 feet to an unoccupied space you can see that is also in dim light or darkness. You then have advantage on the first melee attack you make before the end of the turn.
You can take one willing creature with you.
Shadow projection
At 13th level you gain the ability to project your shadow to any location on the same plane of existence that you are familiar with in which your mark has been made with charcoal, or within 20 feet of a creature that carries your mark. The target location must be in dim light or darkness. As an action you may cast your senses into your shadow self but are blinded and deafened to your physical surroundings. You may speak through your shadow. You may end this at anytime with no action required. In addition a creature may request your shadows presence by being in contact with your mark and focusing on their desire for contact for 1 minute. You are not required to respond in any way but you are aware of the request.
Death Strike
Starting at 17th level, you become a master of instant death. When you attack and hit a creature that is surprised, it must make a Constitution saving throw (DC 8 + your Dexterity modifier + your proficiency bonus). On a failed save, double the damage of your attack against the creature.