Alright, folks, I need your help.
I read through a version of D&D when I was way younger and loved the lore entries for everything- the monsters particularly.
One monster's entry stuck out to me. It described a beast that slumbered in a cavern at the edge of the world, only to be awakened when someone on the material plane would speak it's name three times, whereupon it would cut a swath through the living world until brought down again. Subsequently, to speak the name was taboo in all societies.
Here's the catch. I don't remember which book the monster was in, what edition of D&D it was, or almost any other details. That little wisp of a memory is all that I've got.
I'd like to know what, exactly, that creature was, just so I can find it again with the other source material that I read at the time. I will likely remember the name when I read it, and TVtropes has failed me, so;