Secrets of Creation and Jailer's Plan Revealed in Zereth Mortis Books (Spoilers)

wowhead.com:

One of the developing themes of Patch 9.2, currently on the PTR, is secrets. Finding secrets, unlocking secrets, deciphering secrets. With this in mind it should come as no surprise that there is a book collection activity in Zereth Mortis, Firim in Exile.

These books talk about how Firim became an exile in Zereth Mortis, his interaction with the automa of Zereth Mortis, and at the end, talks about the plans the Jailer has. Collecting the parts of Firim's book is required for the achievement Tales of the Exile. This achievement is, in turn, part of the requirement for another achievement Unlocking the Secrets which unlocks flying in Zereth Mortis.

If you are interested in the requirements for flying in Zereth Mortis, check out this post: Zereth Mortis Flying Requirements Changed For those who enjoy lore, however, Firim's work is a treasure trove in itself.Warning, PTR SPOILERSFirim is a broker who we encounter early on in our trip to Zereth Mortis.

But the brokers in Bastion do tell of an expedition that went missing long, long ago. Firim: Missing? Hardly! I succeeded in finding this realm of knowledge and wonder. A place of tranquility… until the Mawsworn attacked.

Pelagos: I see no Mawsworn here. Where are they? Firim: The Jailer's forces are spreading like a plague across Zereth Mortis. No doubt he seeks entrance to the Sepulcher.

Firim: The secrets of the cosmos lie within. Be wary! His agents could be anywhere... Pelagos: What manner of constructs are these? Firim: They are called automa.