I'm in the Chancel, having just met Agrippa in the area before. There's a Hemispherical Deression and an Orb the game keeps ranting about, but nothing I can seem to do about it. There's an altar I can't do anything to, some levers I can't pull, a door I can't open and a tunnel full of electricity I can't pass, right next to the hemispherical depression. I can pour some tar in the depression and that's about it, but nothing seems to change.
What do I do here? I'm clearly supposed to find some orb, but where and how?