Dungeons

"Let me give you something else for free, eh? I must be feeling very generous, my Varangian friend. Don’t go underground, even during the day. Everyone should know that, but I worry about you. The monsters that roam the city at night, they hide from the sun in the dungeons that form below the surface and in the hidden places of the city."

- Asylaion, Chapter 5 of Book 1

Dungeons form when a monster makes its nest. The longer a monster spends in the same spot, the more magic will warp and twist the area around the nest, causing more—and stronger—monsters to either evolve or show up. 

Dungeons run on something called a dungeon core, which empowers the entire dimension and makes it self-sustaining.

What this means, in practice, is that the longer a dungeon goes without being cleared, the stronger it gets, creating a vicious cycle that makes dungeons even stronger and even harder to clear as a result. Given enough time, a dungeon can even end up as a portal to another dimension that is anything unlike this world.