You focus your training on the grim art of death. Those who adhere to this archetype are diverse: hired killers, spies, bounty hunters, and even specially anointed priests trained to exterminate the enemies of their deity. Stealth, poison, and disguise help you eliminate your foes with deadly efficiency. 

Tools of the Trade

When you choose this archetype at 3rd level, you gain proficiency with the disguise kit and the poisoner’s kit. You can apply poison to a weapon or piece of ammunition as a bonus action.

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 is at full health or that hasn’t taken a turn in the combat yet, in addition; any hit you score against a creature that hasn't taken a turn in combat yet is a critical hit.

Deadly Quick

Your training and experience has taught you how to strike fast and strike hard at the unsuspecting. Starting at 9th level, you can add your proficiency bonus to your initiative rolls. You also upgrade your sneak attack dice to d8s.

Debilitating Blows

At 13th level, you gain the ability to strike your opponents with such force and precision that it leaves them vulnerable. Whenever you critically hit an opponent and deal sneak attack damage they are stunned until the start of your next turn.

Death Strike

Starting at 17th level, you become a master of instant death. When you attack and hit a creature that hasn't taken a turn in this combat yet, 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.

Additionally whenever you deal sneak attack damage you can treat all 1s and 2s on your sneak attack dice as if they were 3s