In this world, dungeons could spontaneously appear if a place was suitable for it. But that place would not immediately turn into a dungeon. Instead at the very beginning, a seed of a dungeon core would appear. It would only be able to summon a single familiar to protect itself while the seed needed time to adjust itself according to the location.
This adjusting process was very complex and it could take from just a few days to a few years depending on the location. During this time the core would give off a peculiar aura which was very attractive to monsters, animals or other powerful beings.
For the intelligent races, the seed of a dungeon core was a very rare and expensive material. It could be used in many alchemical creations. As for monsters and beasts, consuming a seed of the dungeon core would increase their level and stats. At the same time it could also strengthen their bloodline. So monsters and beasts were also greedy for a seed of the dungeon core.
