Trick to that one - and to any perdition rock exploring/skill capping trip - is to be patient once you arrive . Wait until the patrols start moving right and stick to the wall on your left as much as possible .
Do it with henches , no problem there , once you arrive at the seal kill it ( don't venture left or right just kill the seal . Pass the seal to the right and go straight ahead to the path leading towards the north.
You should already see the first badge of white mantle once you passed the seal .
Make sure to take out the breeze keepers ( they patrol and if you don't take them out they'll appear in your back ) which will appear to your left .
There's a hydraboss-spawn to your left - where the breeze keepers are - and it's a random boss , but he carries an elite
Problem for most people with final blow is that they don't wait for those hydra and flesh golems patrols to move out of the way but simply run forward immediately . Then you will most definitely get swarmed
If you still can't make it with henches , try a random team- at least one will have done it already and will know the "patrol-trick "
IGN: Isis of Durnham ( only if you are totally stuck !)