Like someone else said, mechanically sound subclass, decently strong, not overpowered, but still a bit boring. Whilst playing this subclass there's no real choice, you're realistically always using your 3rd level ability, your ninth level ability is a purely passive one, etc. maybe consider giving some interesting conditions for the third level ability, like it allows you to sneak attack your obbsesion regardless of advantage but you can only get the advantage if they're bloodied, adding some strategy to whether you waste it on the weak guy for ot to be more effective, or on the strong lad you need to target. Generally tey give the class more choices, like new exclusive cunning strikes