Activate Protection Stones to open doors.
Go down the stairs on the right to activate one stone, then the two at the door. Dark elves and goblins will spawn when you click the single stone.
Cross the bridge and kill 2 shamans. Down the stairs to the right is a chest, to the left a stone. Activate the single stone to unlock the 2 stones at the door. Bats, goblins and an orc spawn when you touch the single stone, goblins and a dark elf when you approach the chest.
In the clearing before you stand three large dark crystals (pictured in the Quick Facts box, above). Directly behind each is a barricade. Each time you smash a crystal it destroys a barricade and releases a minotaur. Move to the side as he emerges! From time to time they power up and smash... try not to be standing there when they do it. You may want to avoid unbroken crystals as you CAN get all three at once! Where the minotaur came from is a stone you need to activate.
Boss: Umnod the Minotaur
Oddly enough, for a melee fighter the safest place is under his belly as his axe attacks will actually overreach you!
The evidence you seek for The Ring Thief will be here once Umnod is defeated.
There are no mobs to fight here, just quest actions to take. If you do not have a quest that needs to come here you will not activate the door when you kill Umnod.
When you complete Power Down and get Dark Elf in Red, and after the cutscene with Elena and Stompy, you will be transported to a clearing (in Marauder's Lair) to witness Gobspids transformation into Hobspid the Hobgoblin, then you must fight him! Afterward, you will be dumped out in Ashen Ruins (so loot fast).