They continued cautiously, and soon they stumbled upon an opening that revealed a vast underground chamber. The ground beneath their feet vibrated subtly, and what once was a sewer now resembled the entrance to a dungeon. Dark stone pillars rose from the floor, twisted and malformed, and the faint hum of magical energy filled the air.

    Luna looked up at Leon, her expression serious. "This isn''t just an underground tunnel anymore. It''s turned into a dungeon."

    Leon frowned, his gaze scanning the surroundings. "A dungeon forming in the middle of a city... This could be a problem."

    The formation of a dungeon is a natural yet dangerous process. It begins when a monster nest is left unchecked, allowing a Dungeon Core to find the area and merge with the nest. Once merged, the core slowly takes control, turning the entire area into its domain and empowering the monsters that inhabit it to act as its guards.

    Over time, the monsters evolve under the influence of the core, becoming stronger and more vicious.

    A Dungeon Core itself functions like an egg, gestating and growing until it''s powerful enough to give birth to a demon lord. As it matures, the dungeon evolves in strength and complexity, becoming more dangerous with each passing day. Dungeon Cores are not simple objects, though—they are actually Demon Seeds, entities that search for suitable nests to "hatch" themselves into fully-fledged demons.

    The type of demon birthed depends on the grade of the dungeon at the time of its hatching.

    For instance, the dungeon Leon and Luna now face is currently a simple Grade 1 Dungeon. If left unchecked, it can evolve into higher grades over time, allowing the core to eventually hatch a higher-tier demon. Right now, the core is capable of birthing a Peak Tier II demon.

    But if no one interferes, the dungeon could continue to grow, evolving from Grade 1 to Grade 2, and beyond, birthing even more powerful demonic entities.

    "The core is probably buried deeper inside, protected by all these monsters," Luna remarked as they observed the area.

    Leon nodded, his gaze focused. "Then we need to clear this place out before it evolves any further. Otherwise, we might be dealing with something far more dangerous than a Tier II demon."

    Luna, standing beside him, nodded grimly. "This is where the core''s influence is strongest. We''ve definitely entered the dungeon''s heart."

    Since , this is only a Grade 1 dungeon, this is only a single floor or single room dungeon, leading them to arriving directly at the center of Dungeon where the core is located.

    The air felt thick with power, almost suffocating, as they stepped further inside. Strange, twisted creatures scurried along the walls—creatures neither fully rat nor fully demon, their bodies a grotesque mix of fur and scales, their eyes glowing red with malevolent intent.

    These were the dungeon''s defenders, the plague-ridden rats now fully transformed into monsters under the Dungeon Core''s control.

    Leon flexed his fingers, summoning his Aether magic. "Get ready. This is going to be a rough fight."

    Luna drew her weapons, her eyes narrowing as she surveyed the enemies around them. "I''ll take the ones on the left. You handle the right."

    With a nod, they split off, moving swiftly into battle. The rats shrieked and charged at them, their claws clattering against the stone floor as they swarmed the duo. Luna''s movements were fluid and precise, each strike of her blade dispatching a rat in a single motion.

    Leon, meanwhile, summoned bursts of energy, hurling Aether bolts at the creatures, incinerating them before they could get too close.

    Despite their strength, the enemies seemed endless, pouring from hidden cracks in the walls, as if the dungeon itself was birthing them. The chamber reverberated with the sound of battle, each clash of weapons and blast of magic echoing through the room.

    "These things just keep coming!" Leon shouted, panting slightly as he launched another spell.

    "They''re buying time!" Luna replied, her voice sharp. "The Core must know we''re here!"