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Dungeon Mutation, a phenomenon where Dungeons would change their effects, main elements, or even monsters in a whim, happening randomly between fluctuations of Mana and Miasma in their interior.
Usually, there are two types of Dungeons out there. Wild Dungeons, created from Miasma in an area, which are usually dangerous but don't spawn monsters constantly, and can be completed by cleansed of the Miasma. They often appear when a lot of Demons die and leave their blood rotting into miasma.
And then there were Artificial Dungeons, created according to Alberta and Hellburn, by the Divine Spirit of Dungeons, a lesser being to a Holy Spirit that is attempting to ascend into a God.
It is said that his existence is similar to Yggdrasil too, beings that are like Holy Spirits, but not quite yet, Demigods. This Spirit of Dungeons is said to have been the Ancestor of all Dwarves, the Architect King.