I fully swept through the second part of the dungeon three times now, even checking the little side rooms and i'm stuck on Destroy blood boils: 1
So I can't even complete the dungeon after using a nightmare sigil on it. : /

There was a main boss now, Lord Isemberd Shivermaw, a caster. Is surrounded by three bloodboilt and summons the selection of elites you fough through the stronghold. After slaying him, your char states "You will never harm another soul". You can then clear the stronghold, but like with the others it stays occupied by ghouls and no new inhabitants.