Mysterious chronicle (part 15) is obtained in Daemonheim, while Dungeoneering. It is sometimes obtained after killing a boss monster at the end of a dungeon, along with another piece of armour or weapons.
It was written in the year 1641 of the Fourth Age. Bilrach asks if it is fate that he makes significant progress on the 400th anniversary of his start date. Bilrach says is nearing the half-way mark, and he believes he is getting more powerful the deeper he goes, and that soon he will be at The Rift.
This is the first chronicle that references the Rift. Previously he had seemed to just figure out what would have been at the bottom, but he now has a name for it.
Year 1641 of the 4th age:Is it fate that significant progress is made on the anniversary of my start date? Four-hundred years of careful destruction and here I am, nearing the half-way mark! If I can make it half-way, I can make it all the way. I swear my power increases the deeper I go. It will not be long before I unleash on this earth. I will be closer to the end than the start. Soon, I will be at the Rift!