Sneaky Steps
At 3rd level you've dedicated your methods to heists and big scores. As such you've learned how to evade direct confrontation. When you use your Cunning Action you can use any combination of the two actions listed for a single Bonus Action. Additionally you gain a 1d4 bonus to your Stealth checks when taking the Hide action.
Off With the Loot
You've learned to swipe and swindle with the best of them. At 7th level while hidden the Disarm action is added to your list of available actions for Cunning Action. When you disarm a creature if you are proficient with the weapon you may make a single attack with the weapon as a free action. Once per long rest if you remain stationary for one minute you can use the Invisibility technique costing no energy.
Knapsack
A burglar is nothing without their bag and your no different. At 10th level you gain an additional item interaction on each of your turns. Additionally a number of times equal to half your proficiency bonus per Long Rest you can reach into your Knapsack as a free action to pull out one of the following. An item used from your Knapsack has no sell value, lasts for only 8 hours, and can be used by you as a Bonus Action.
Greater Bandages
Lock Picking Kit
Greater Fire Bomb
Caltrops or Ball Bearings
Additionally you can fit an object that is under 500 pounds and under 15ft cubic square feet into your Knapsack and suffer no movement penalties regardless of your Strength score.
Stolen Concentration
The best burglars know that to succeed in a heist you need to take their attention and put it elsewhere. At 14th level when the target of your 'Thieves Mark' is at maximum stacks you can attempt to steal the effects of a Concentration effecting that target as an action. If you do so they must make a Wisdom Save versus you Brawl Save DC or you gain the effects of that concentration effect and they immediately lose its effects.
While under the effects of a Stolen Concentration effect you can maintain concentration on the effect as if you cast it, this does not impact your total concentration effects. Once you have used this feature you cannot use it again until you finish a Long Rest.
Ultimate Heist
Your plans are flawless and a heist rarely goes wrong for you. At 17th level as a reaction to being targeted by a melee Technique or attack from an enemy creature you can attempt to take something from your attacker. Make a Slight of Hand check contested by their Insight. If your Slight of Hand check beats their Insight check you can choose one of the following to take from them (they lose and you gain) until the end of the encounter. You can do perform this reaction once per creature per encounter.
1 AC
2 on a save of your choice
5 DR
5 Movement Speed