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. As your mastery in assassination progresses you will become a master of instant death, able to silence foes foolish enough to lose sight of you.

Bonus Proficiencies

When you choose this archetype at 3rd level, you gain proficiency with the disguise kit, the poisoner’s kit and the hidden blade: a concealed trick dagger mounted on the wrist.

The Unseen Blade...

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.

Mask of Many Faces

Starting at 9th level, you can unfailingly create false identities for yourself. You must spend seven days and 25 gp to establish the history, profession, and affiliations for an identity. You can’t establish an identity that belongs to someone else. For example, you might acquire appropriate clothing, letters of introduction, and official-looking certification to establish yourself as a member of a trading house from a remote city so you can insinuate yourself into the company of other wealthy merchants.

Thereafter, if you adopt the new identity as a disguise, other creatures believe you to be that person until given an obvious reason not to.

Death's Touch: Know Thine Enemy

Starting at 9th level, your lethality when you get the drop on your enemies sharpens further and your ambushing skills become deadlier. When you attack (and hit) a creature unaware of your presence, make a intelligence (medicine) check (DC: 8 + half the creature's Challenge Rating) to identify a weak point. On a success, treat this attack as a critical hit dealing double damage instead of double the dice.

Imposter

At 13th level, you gain the ability to ,nearly flawlessly, mimic another person’s speech, writing, and behavior. You must spend at least three hours studying these three components of the person’s behavior, listening to speech, examining handwriting, and observing mannerisms.

Your ruse is indiscernible to the casual observer. If a wary creature suspects something is amiss, you have advantage on any (Deception) check you make to avoid detection.

...Is the Deadliest.

Starting at 17th level, you become a master of instant death. When you score a critical hit on a creature that is unaware of your position (as with being hidden), it must make a Constitution saving throw (DC 8 + your Dexterity modifier + your proficiency bonus). On a failed save, triple the damage of your attack against the creature instead of doubling the dice. This feature does not stack with Death's Touch: Know Thine Enemy.

The creature has disadvantage on the saving throw if it is surprised.