You are so so good at killing people, they dont even know you can kill them till after they die

assasinate

you have advantage on attack rolls against targets that haven't taken a turn in combat yets. any attack scored this way is a crit

Infiltration expertise

While 9th level may seem far away, if you can get there, things get interesting. With one week and 25 gp, you can create an entirely new identity, complete with a background, a profession, and even connections.

You can’t steal someone’s identity; you can only create new ones. These can help you get into secret societies, events and snag bargains at the market. It can also be helpful if you need to hide your identity.

When you do create an identity, other creatures don’t make checks to find out if you’re not who you say you are unless you give them a reason not to believe you. They will passively believe you are who they see before their eyes.

Impostor

At 13th level, you can mimic someone else’s speech, writing, and behavior patterns. You have to study them for three hours and then you can uncannily copy them. However, others can become suspicious if you make a mistake.

You gain advantage on any Deception check you make when trying to pass off as someone else. So when you roll for a disguise Deception check, you roll twice and use the higher number.

Death Strike

By the time you reach the 17th level, you are much more dextrous and sneaky. When you attack and hit a surprised creature, it has to make a Constitution saving throw (DC 8 + your Dexterity modifier + your proficiency bonus).

If it fails, then you can deal double damage to the next creature that you attack. Hop on one and then to the next, critical striking wherever you go. I cannot explain how fun this is to do.