Soul Snatcher

With their natural affinity to steal, these rogues can even take intangible things, such as vitality, perception, and even memories. Often descended or blessed by a succubus, incubus, vampire or other supernatural thieves, these rogues often have a habit of stealing things that normal ones cannot, just for the thrill or to become infamous.

Siphon Strength

Starting at 3rd level, you can use the bonus action to attempt to steal the strength of an opposing creature. They must make a wisdom saving throw of DC 8 + Proficiency + Charisma modifier, on a failure, until the end of your next turn, they have disadvantage on attack rolls, saving throws, and skill checks, while you gain advantage in all of those. You may use this ability a number equal to your proficiency bonus, regaining on a long rest.

Thief of Thieves

Starting at 3rd level, you can know steal someone else's skill. You can touch another creature and gain proficiency in one skill they are proficient in. While you have it, you can choose if the person you stole it from retains their proficiency. You cannot take someone's proficiency if you are already proficient in that skill. This lasts until you fall unconscious or you use this ability again. At 13th level you can now take 2 proficiencies at the same time. 

Silent Step

Starting at 9th level, you naturally steal the perception of all enemies around you. You do not provoke opportunity attacks if you did not start your turn within range of that creature.

Raid Memories

At 13th level, your can even steal memories. Once per day you can cast modify memories, DC = 8 + proficiency + Charisma modifier. When you do so this way, you can only steal memories, not add any to the target. Memories stolen this way will fill in with a natural progression of events.

Rampant Plunder

At 17th level, you can push all of your skills to the limit and steal all the strength that you can. Once per day you can use your bonus action, and target up to 5 creatures within 60 feet of you. They each must make a wisdom saving throw against your Siphon Strength DC For those who fail, they have disadvantage on all attack rolls, skill checks, and saving throws for x turns, where x is the number of targets who failed. You gain advantage and +x to all attack rolls, skill checks, and saving throws for x turns, where x is the number of targets who failed. After the allotment of turns, you gain a point of exhaustion. Also at this level, your Siphon Strength ability refreshes on a short rest.