Orpheu, after entering the dungeon, found all his students on the first floor with a few stragglers coming down from the second floor.
"Professor." One of the students called after seeing him. "There's something wrong. The tower is filling with miasma coming from the higher levels. And all the windows got shut down."
Orpheu looked around, some of the students had ulcers and blackening of their skins due to the contact with miasma. A couple of students who had the Priest class were treating them.
"Okay. Just get out…" Opheu tried to guide his students out, but suddenly the gate closed behind of him. "...side."
Orpheu realized then what was happening. This has happened before on that dungeon. Using unholy mana inside of it caused a dungeon fluctuation which created unholy mana and made an undead horde come down from the 50th floor led by a Dullahan, a flesh undead clad in heavy armor, riding an undead horse, who had no head. A level 30 monster in most cases.
