I did “The Hidden Path” for the first time 3 days ago. I just needed a nudge for the first part, the location of “Runestone of Dreeg”. From there, I was able to find my way for the other Runestiones, and finally, “The Temple of the Three”.
As a Demolitionist, one doesn’t just charge into battle and hack away at The Sentinel. Right outside the locked gate of “Sanctum of the Witch Gods”, I noticed how slow the gate was in closing… so I planted a Mortar Trap right inside his chamber and dashed back outside before the gate closed. I re-opened the gate for a few secs to toss in a Canister Bomb and ran off. Now THAT got his attention!
The Sentinel stood behind the locked gate, with me outside, free to run off, heal up, open a Riftgate or go anywhere. Thru trial-and-error, I found that shutting off the map, and standing on the stairs across from the locked gate was the sweet spot. His green ball attacks did little damage, so I stayed on the stairs, tossing Grenados and Canister Bombs at him continuously. Since he was stuck behind a gate that he couldn’t open, it wasn’t that hard to defeat him. Now I’m beginning to think of “The Sanctum” as prime iron-bits farming. 20k in iron bits!