Base Class: Rogue
Those who have fought shadow dancers describe the experience as similar to fighting a living darkness. Every dim alcove and darkened nook is a place from where the lithe and acrobatic shadow dancers can emerge to ambush their prey.
Shadow Step
At 3rd 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 60 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.
Umbral Sight
At 3rd level, you gain darkvision out to a range of 60 feet. If you already have darkvision from your race, its range increases by 30 feet.
You are also adept at evading creatures that rely on darkvision. While in darkness, you are invisible to any creature that relies on darkvision to see you in that darkness.
Assassinate
Starting at 9th 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.
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.