Mysterious chronicle (part 8) is a book found only in Daemonheim. It may appear in front of the dungeon-ending ladder after killing the boss monster.
It written in the year 1403 of the Fourth Age. The floors above have begun to freeze, forcing Bilrach's servants downwards. He states that they will continue to follow him for as long as they are useful.
Year 1403 of the 4th Age:
It turns out that I was right: the area above has begun to cool to freezing. My servants are moving deeper with me; it was pleasant to see them do it voluntarily for a change. Perhaps they believe themselves to be with me in this great descent? Ha! They'll last as long as their use permits, and they'll follow me deeper if they want to survive. As if I'd stop to maintain an area for them to live in!Zamorak be praised!