Oublivants: a category of dungeons characterised by the antithesis of life, necrosis.

"Dungons as a whole tend towards the lethal side when it comes to exploring them; however, an oublivant actively seeks out destruction on a grand scale. No greater example of their deep hatred for life exists than the very first discovery of an oublivant. It was a massive dungeon spanning miles in all directions. It continuously expanded along the surface, so fast you could see it, and left nothing but a scorched, withered wasteland in its wake. Wherever the oublivant resides, nothing but the undead exist, as all living life has been eradicated. Why it is, exactly, the oublivant seem so against life so as to break the passive rule dungeons have is unknown. What is known, however, is that they're a threat that, upon discovery, is to be immediately eliminated." - Archomagus Addiom Onero, Court of Vascil
Note: This is my first story on royal road. It'd be nice if you were nice... nicely.