Sometimes DMs put a lot of thought into their homebrew setting and like anything else it can be more interesting than what ever is going on, like trying to remember Jacob's name.
So... I had the idea that the villain of my game would be a sort of "folk hero" who wrote (and often greatly exaggerated) records of his adventures. Being a bard, he found a way to achieve eternal life through his stories; as long as people kept reading about his adventures, he would maintain his undeath. Worked great until he realized he would need to create new stories to keep people interested. No problem, he could just create a demiplane where adventurers would come in search of treasure, and transport them into perilous and outlandish situations. Now he has new material for his stories! Hopefully they don't catch on to the fact that these stories are made up... because then he'd have to make sure they could never leave...