It's a horror story about a mysterious and malevolent being known as the Dweller in Darkness. It often involves dark and spooky elements like an old, abandoned place where this entity lurks, waiting to bring fear and chaos to those who encounter it.
Well, a 'dweller monster story' could center around the existence and nature of a monster that dwells somewhere. It could be about how this monster came to be in its dwelling place, what it does there, whether it preys on the local inhabitants or has some other purpose. For example, it could be a story of a monster that dwells in an abandoned mine and how it affects the nearby town, either by causing disappearances or by just creating an air of mystery and fear.
Once there was a dweller in an old, abandoned house. One night, he heard strange scratching noises on his window. He peeked out, but saw nothing. As he went back to bed, the scratching grew louder. Suddenly, a pale hand reached through the window, and he ran out of the house screaming.