I'm not sure specifically as there could be many novels with such a title. Generally, it might involve a death knight who has some sort of lordship or power. Maybe it's about his battles, his rise to power, or his conflicts with other forces in a fantasy world.
The Death Knights in the Overlord novel are powerful undead warriors. They are often depicted as having great physical strength and being highly resistant to damage. They are loyal servants of the overlord and play important roles in battles and the overall power structure within the story.
Since I haven't read it, I can't say for sure. But it might have the death knight himself as a main character, of course. There could also be characters like his loyal servants, perhaps other powerful dark mages or warriors who serve him or oppose him.
Sebas Tian is also a notable character. He is a butler - like figure with great strength and a sense of honor. He is involved in various missions and interactions, and his relationship with other characters, especially his loyalty to Ainz, is an important aspect of the story.
Well, in the Overlord light novel, Clementine's death is quite a memorable part. She had been a somewhat devious character, causing trouble here and there. But as the story progresses, she gets caught up in a web of events that she can't control. Her death is a consequence of her alignment with certain forces and her own miscalculations. She faced off against opponents who were stronger and more cunning, and in the end, she was defeated and died.
Clementine's death in the Overlord light novel is important for several reasons. Firstly, it was a turning point in some story arcs. Her actions before her death had caused a lot of chaos and her demise brought a sense of justice or at least a rebalancing in certain areas. Also, it demonstrated the might of the main characters or forces in the novel. She was a formidable character in her own right, but her death showed that there were far more powerful entities in the world of Overlord.