[Trexmaster]

After leaving a fight in a crazy spacey stylish level 70 fire altar, I was greeted by this instead of the floor proper. Almost the entire floor was replaced with black tiles, and walls, chests, or stairs were also deleted due to this, making the floor inaccessible from either end, and making progress impossible.

I've had this happen before awhile back, but only a small portion of the dungeon was affected, and it was as soon as the floor was generated upon going down the stairs.