While exploring a cave near Marilun, adventurers from the local town were caught in a near-cave-in that altered their route out to force it to pass through this library. It appeared to have been sealed in stone in the nearby mountain, perhaps in an attempt to preserve it.
The books inside all date back to the pre-Miasmic Age, although not all of them are of interest — it’s a vast library, after all. Also, some of the books try to bite you: the party has encountered at least a few Mimic Books.
Map Room
In the east wing of the library, the party found a vast map, much more modern than anything in the library, occupied by mysterious playing pieces that could not be moved. If watched, some of them seemed to move. One piece — lying on its side near the city of Orologio — was the exception to the rule and could be picked up, and was taken by Serafina.
When queried about what this map represented, the Mysterious Grimoire explained that it most likely represented troop movements and was tied to something that those troops carried in their possession; Cynthia was able to confirm that the pieces (save for the one Serafina had, whose connection was broken) all contained a sort of sympathetic magic that radiated out of the library map room to points unknown.