Through your training you have studied and mastered the art of death, familiarising yourself with enemies' vitals and their weak points. You have learnt to efficiently and effectively use poisons, blades and a silver tongue to achieve what you want, concealing yourself to achieve surprise attacks.

Tricks of the trade

When you choose this archetype at 3rd level, you gain proficiency with the disguise kit and the poisoner's kit.

Assassinate

Starting at 3rd level you may expose the weaknesses of foes, achieving a critical hit on a natural 19. Additionally, when you critically strike, you may make a DC (10 + Enemy Dex Mod) Intelligence (Medicine) check to expose a vital, giving the next melee weapon attack against the target advantage.

Master of the unseen

Starting at 9th level, you receive a +3 modifier to all Dexterity (Stealth) checks. Whilst hidden, if you are wielding a melee finesse weapon that you are proficient with, you can choose to take a -10 penalty to the attack roll. If the attack hits, you add +10 to the attack's damage.

Chameleon

At 13th level, when you have studied a target for a minimum of 3 hours, you may attempt to adopt their mannerisms, speech and handwriting. You have advantage on all Charisma (Deception) checks to avoid detection whilst using this guise. Additionally, whilst attempting to conceal yourself within a crowd, you may receive advantage on a Dexterity (Stealth) check to blend in; you may only use this feature once per short rest.

Improved Sneak Attack

At 17th level, when using Sneak Attack, you may reroll any 1s rolled, keeping the resultant roll. Additionally, once per long rest, you may "Execute" a creature, instantly killing a creature with 100 or fewer hit points if they fail a Constitution saving throw against your Rogue level. Otherwise, the move has no effect.