Plunderer OTK

Ok, here's an OTK I want to try. The idea is to play Umbral Skulker, Shadowstep (twice if possible), then use Silas Darkmoon to give your opponent a Soulbound Ashtongue and hit it with Prize Plunderer for lots of damage. I don't think you can get to 30 without also throwing in a Backstab or two and a Preparation/Eviscerate combo or something.

Any thoughts or suggestions?