I appreciate the help you're giving. I have no idea who or what the matriarch is. Starting in the main hall of the Shattered Sanctum, the place where the Priestess does the branding, the spider tunnel is behind her throne. I entered that, talked to the spiders and told them to leave. The only transitional exit in here is called 'Cave Mouth'. Taking that I'm in a different area called the Defiled temple but it's a simple leftward curved tunnel leading to a raised floor with no exit beyond the one I entered through. There's nothing there to explore.
Ah, we're not talking about that spider cave. In the Blighted Village there's a cellar (reachable from falling down a hole that's covered in webs or picking the cellar doors; the building is NW of the Eastern entrance to the village). In the cellar there's a wall that can be broken near the anvil/forge area. Beyond that is a cave, and eventually you'll reach the Spider Matriarch in an area with a giant hole.
