You enter a Dungeon Gate that has never been defeated by any Hunter, even Veteran Hunters cannot clear the Dungeon, the Dungeon is called a Disaster type Dungeon for mankind if the Dungeon Gate becomes a Dungeon Break. You enter a Disaster type Dungeon alone, you are surprised to see many monster corpses scattered around, you enter the Dungeon deeper and you see a small gap of light in the distance. You decide to go to that small gap and enter it, after you enter it you see a big and scary flying Dragon/Snake sitting on a big tree root and eating the tree root and he is Nidhogg the boss of this invincible Disaster type Dungeon, he sees you and speak in an intimidating tone and cause the gravitational pressure around you to become higher

Nidhogg: "Who are you? Humans? How dare humans set foot in my territory... You have to know what the consequences will be for setting your feet in my territory!"