became a true master of death. 

Death mark

Starting at 3rd level, you can use a bonus action on your turn to mark an enemy for death until the end of your turn. When you hit a marked target with a weapon attack taht could benefit from sneak attack, you expend the mark and cause the attack to be a critical hit.  

you can use this ability an amount of times equal to your proficiency  bonus and regain expended uses after a long rest. 

Master of death

When you choose this archetype at 3rd level, you gain proficiency in the poisoners kit and disguise kit. 

 

Flawless Death

Starting at 9th level, if you would reduce a creature to 0 hit points as a result of scoring a critical hit with your Death Mark, you may regain one use of Death mark. 

Hide in shadows.

By 13th level, you have mastered the ability to infiltrate and assassinate.  your death mark now expires after 1 minute, instead of the end of your turn. you can only have one target marked at any given time. 

Furthermore, you have advantage on sleight of hand and stealth checks made against marked targets. 

Death Chain

When you reach 17th level, you have mastered the art of death. if you would reduce a creature to 0 hit points as a result of a weapon attack using sneak attack, you may then make a  melee weapon attack on the nearest enemy. You may use any leftover move speed to get to the target, but you cannot exceed the movement speed for the turn. you may treat the attack as if you had not used sneak attack this turn. repeat this process until one of your attacks fails to reduce a creature to 0 hit points. 

once you use this feature, you may not use it again until you finish a long rest.