An invisible Assassin build, you start with being invisible, right before combat proc [Rage] and [Fast Movement] than on a single target use [Hard Cut] to engage and than [Plunge] to stun and stop them in their track and than [Perforation] to consume your stacks, [Cleanse] is used right after to silence the target; remember to use it on you way before you fight to prepare yourself for the mages. [Phantom Blow] after, with [Rage] still active you should have 4 stacks [Whirlwind] for that last attempt at damage than use [Prestidigitation] and [Instantaneous Impact] away while keeping an eye on your skill reset, spamming them until you're about to get stun from [Rage]. Right before you get stun you [Bubble] than/or [Backflip] than go invisible to get stun while invisible.
[Bolt of Heaven] is used to cast up if they run away, but spam it too if needed. [Scream of Fear] can be combine early with [Perforation] to knock the target down if the cc is needed, but I find the main purpose of it as the set up for [Broken Spirit] to heal you when the healing is needed. [Bubble] is used to get some CD time when you need to back off.

To engage a group you start with the same two buffs with [Prestidigitation] than engage with [Bolt of Heaven] and [Whirlwind], proc [Break Chain] and [Wake Up!] when needed but your goal is to use [Scream of Fear] to CC the whole group while you [Shadowstep] and single one person out until the cc is over and rinse and repeat the reset proc tatic or [Backflip] out of the fight to plan something else.