Assassination rogues are deadly masters of poisons who dispatch their victims with vicious strikes.

Assassinate

3rd-level Assassin Archetype feature

As an assassin you are at your deadliest when your foes have no time to react. You gain the following benefits:

• After initiative order is determined, you can expend     an Exploit Die and add it to your initiative roll.

• You have advantage on weapon attack rolls against any creature that has not yet acted in combat.

• Whenever you hit a creature that is Incapacitated or Surprised with a weapon attack that adds your Sneak Attack bonus, it becomes an automatic critical hit.

Assassin Exploits

3rd-level Assassin Archetype feature

You learn certain Exploits at the Rogue levels noted in the table below. They don't count against your total number of Exploits Known and can't be switched on gaining a level.

Rogue Level - Exploits

3rd - Precision Strike, Subtle Con

5th - Craft Minor Poison, Crippling Strike

9th - Craft Greater Poison

Infiltrator

3rd-level Assassin Archetype feature

You are adept at blending in where you don't belong. You gain proficiency with both disguise and poisoner's kits.

Over the course of 10 minutes, which can be during a short or long rest, you can use your disguise kit to craft a disguise that resembles a dead or Unconscious humanoid, so long as you have its body. This disguise is detected by a successful Search action against your Exploit save DC.

Finally, you can unerringly mimic any humanoid's speech, so long as you have spent at least 10 minutes listening to it.

Deadly Blades

7th-level Assassin Archetype feature

You are exceptionally skilled at taking lives when conditions are right. When you score a critical hit and roll a 1 on any of your damage dice for that attack, you can re-roll those dice.

Also, whenever you add your Sneak Attack bonus to an attack, you can use Cunning Strike to reduce that bonus by 1d6 to force the target to make a Constitution saving throw against your Exploit save DC. On a failed save, the creature is Poisoned until the beginning of your next turn.

Flawless Infiltrator

13th-level Assassin Archetype feature

The skill with which you adopt other creatures' identities is nearly supernatural. You learn to speak, read, and write three additional languages of your choice, and whenever you make an ability check to maintain a disguise's credibility, you gain a bonus to your roll equal to your Exploit Die

In addition, you also add your Rogue level to the DC of any check a creature makes to see through your disguise.

Master Poisoner

13th-level Assassin Archetype feature

Your skill with poisons exceeds that of all others who study the toxic arts. You can use any Devious Exploit you know that allows you to craft a poison (such as Craft Minor Poison), and apply that poison to a weapon, with one bonus action.

You also learn the craft advanced poison Exploit, but it does not count against your number of Exploits Known.

Death Strike

17th-level Assassin Archetype feature

You have become a master of instant death. When you add your Sneak Attack damage bonus to a weapon attack, you can choose for that attack to be an automatic critical hit.

Once you use this feature you must finish a short or long rest before you can use it again.