I had been stuck at the 5th round for awhile and like a dummy, I abandoned the quest. Then I was stuck at the second round all week til last nite the stars lined up and I finally beat the centurion thugs. What an awesome feeling it was when they were below 25% health and I could execute them with killers blade and I KNEW I was going to finally beat the level.
I have been playing on my stamblade Orc max CP, 308 skill point, DW/Bow...everything gold but jewelry. I used Nitemothers, Endurance, Skoria, and Leki's axe&1H Mace both sharpened...I think crusher enchants and stamina wrothgar food. I also have 3 piece agility robust...did not seem to help me. I made a stack of Sustained Restore Health potions and they are pretty good I think.
It has never felt like I'm not hitting hard enough. All the adds are easily taken out in one or two hits; i burn the bosses down quick in first cycle then run out of resources and the spinning blade dots overwhelm me. That's why I switched to more stamina recovery build as vigor spamming was quite draining. I tried using the resto staff, but heals from it were really bad on my stam class and I kind of need the bow for dots. Then I tried bone shield. Bone shield sucks. It's expensive and doesn't absorb much damage as it's based on health.
So, my final winning combo was
Refreshing path->endless hail->caltrops->shades->mirage ulti Bolstering Darkness Swap Bloodthirst->surprise attack->killers blade->relentless focus->vigor ulti Flawless Dawnbreaker
Surprise attack is supposed to activate shadow barrier passive, but it often doesn't seem to do it. But shades does quite reliably and the help add a little DPS. Refreshing path is not very good heal, but the speed boost is nice, and I'm not using magic for much else anyways. Mirage...well I don't need shuffle with it and using magic instead of my stamina is a big plus. Also I can be standing still and sometimes get a dodge from the spinning blades.
Tonight I'll start working on the third round and see how far I get. Trying to limit myself to 45 minutes of frustration at a time.