The Underworld Dungeon

After the demon invasion, the mortal world came to know the path of death, destruction, and demonic energy that creatures from the underworld left behind. While many knew the effects of demonic energy or miasma, that the beings from the underworld left behind, not much is known about the effects mana had on the underworld. Which is what the underworld will soon began to know after a dungeon core formed within the lowest level of hell.