This is my current PVE build, based around On Your Knees. I'm having a blast with it so figured I'd share it. I'm currently W/A, but I'm only using one Assassin skill in this particular build. I'm a relative newb, so if anyone spots anything I could do better, I welcome all advice.

Earth Shaker {E}
Counter Blow
Irresistable Blow
On Your Knees
Berserker Stance
Sprint
Shadow Refuge
Endure Pain

Basically, I use Endure Pain or Endure Pain + Shadow Refuge during the pull to survive any spiking and let my healers get into the swing of things. Berserker to build up adrenaline, and from there, I can keep Berserker and Sprint going pretty much non stop using On Your Knees and the knockdowns from Earth Shaker and Counter Blow. I use Irresistable Blow when someone is blocking / evading a lot or to add in a little extra DPS when needed.

Shadow Refuge can obviously be replaced with anything, it was just a handy anti-degen from what I had available to me.