I'm always looking to make awkward setups work in MMOs. It's my job as a theorycrafter, and I think I've hit the nail on the head with this after numerous iterations.
Here's the build: http://arche-base.com/builds/view/49...2/8mBv3vaKBggK
Firstly, I use sword in my mainhand with a katana in my offhand. This gives me the +100% parry chance and highest burst damage potential from sword while also giving me the 100% critical damage chance that the offhand katana passive gives, resulting in constant high damage despite my base physical damage being lower due to the classes I've chosen. The goal is to aim for a balance between both physical and magical damage, as Perforation scales via Magical Damage unlike every other attack in the Shadowplay line.
I'm currently using medium armor, as it provides bonus evade chance and allows me to deal with both magical and physical damage equally, making me entirely susceptible to neither.
The focus of the build is stacking Bloodlust (Deathwish), so attack speed is key. I can typically accumulate an average of 30 Bloodlust stacks, and when backstabbing an opponent with Perforation under the effects of Muscle Failure I deal (108*30*7.5)1.33 damage (32,319 - more than a Meteor critical hit, although this is single-target only). This calculation does not include critical hit chance or damage, and I've seen backstabs ranging up into the 40,000's on light armored opponents. Even so, a good amount of Bloodlust coupled with the right conditions can one-shot a Paladin.
The secondary focus of the build aside from debuffs and high burst is passive healing. The HoT effects do in fact work under the effects of stealth, which make it extremely easy to disengage after a good fear, heal up, and get back in the fight before the opponent has time to reset the fight for themselves.
As for Twilight, it's interchangeable with just about anything your heart desires. I personally take it to give my non-stealth allies the edge when ganking or temporarily cloaking friendlies when escorting trade packs, however you're free to use that skill point however you like.