Shadow Assassin_BaD

You are a skilled assassin, an efficiency sharpened by the dark magic of the Shadowfell. Transformed by its weave, you have grown as a Shadow Assassin, allowing you to blend your stealth with your Sorcery. You intertwine your physical prowess with Shadow Magic to perform your tasks with unparalleled precision and deadly execution.

Shadow Assassins souls are imbued with the power of the Shadowfell, exposed by its dark energy or an entity from that place imposing it onto you. Regardless of its origin you are bound to the dark and utilize it to your very whim. 

Level 3: Umbral Lurk

Starting at 3rd level, you gain the ability transform into a Shadowy Form as a bonus action. During this state you have resistances to Physical, Cold, Poison and Necrotic damage.  You can phase through any non-magical obstacle. You can only maintain this form for up to 1 minute unless you are exposed to Bright Light/Sunlight, rendered Incapacitated or die. If you end this form while inside an object you appear at an open location within 5ft or take 10 force damage if there is no available location.

This ability can be used equal to your proficiency bonus for every long rest.

Additionally gain Darkvision out to a range of 60 feet. If you already have Darkvision from your race, its range increases by 30 feet.

Level 3: Shadow Dodge

At 3rd level, you learn how to land a strike and then slip away without reprisal. During your turn, if you make a melee attack against a creature, that creature can’t make opportunity attacks against you for the rest of your turn.

Level 9: Shadow Strike

At 9th level, once per round, if you perform sneak attack while in your shadow form it deals additional necrotic damage equal to your Rogue Level, and the attack roll needed to critically strike is lowered by 1.

Level 13: Cloak of Darkness

By the 13th level you feel your strongest while obscured in the dark. If you are in an area of dim light or darkness, you are invisible to anyone who isn't within 5ft of you and your movement speed is increased by 10ft. You remain invisible as long as you aren't revealed by light or by a spell. 

Level 17: Death Mark

Upon reaching the 17th level, you can perform a devastating form of Sneak Attack imbued by the strength of the grave. When you use sneak attack on a target during your Shadow Form and it lands you can apply Death Mark creating a festering seal that stores half of the damage you deal to this target. The mark stays on the target for up to 1 minute. You may use a Bonus Action to detonate it within that time. If you do not, it detonates automatically at the end of 1 minute. Once detonated, the Death Mark deals the stored damaged as Psychic Damage.

Death Mark is expelled if you die or if you are knocked unconscious. This ability can be used a number of times per Long Rest equal to your Proficiency Bonus.