Inside the center of the dungeon lies the key. Though it was called that way it doesn't bore the appearance of the real one. Instead, it looks like a giant crystal and has the same amount of mana as a crystal mana. Acquiring the key to the dungeon is essential since this item has the power to manipulate the hidden doors of the dungeon. The hidden doors contain priceless and unique treasures including artifacts. Though they can venture into these places on their own, it would be difficult since they need to leave the direct road which has the most stable amount of mana. If they choose a different path their chances of survival will be slim since they could be killed either by the clashes of energy or by the mutant beasts. The smaller passages are also prone to make people lost and no one has gotten outside who is sane enough to tell the tale of the events there.