PvP: The most common PvP spec (post 3.2.2) is a "deep" Assassination spec, using Mutilate and Envenom for huge burst, relying on the use of deadly poison, which in other specs is generally not ideal, as the ticking DoT can break CC. Another viable spec is Assassination (41/5/25) going down into Preparation in the Subtlety Tree. Since early 3.1, Shadowstep (Hemorrhage or Ambush) specs have become far less common. The most common Shadowstep spec is 20/0/41.