I'm DMing for a group, and the campaign will soon move on into homebrew (started with a slightly tweaked Lost Mines of Phandelver, and a homebrew adventure from the internet will follow). I wanted to start with an homebrew part of my own, starting at the point where the two adventures end, meaning the party starting to find out that an old vampire cult, the Cult of the Black Sun, is active in the area.
The cult's leader is a centuries-old vampire lord, who thinks that vampires are superior to all mortals and would (and should) thus rule over them, the sun being the only thing that prevents them from doing so. A long time ago, he came across a ritual to darken the sun, attempted it once, but got thwarted by a group of heroes. Now he is ready to try it again.
One idea I already had for the ritual was him needing to kill the descendants of the heroes that thwarted him the last time, but that wouldn't make sense if he already attempted to do so - after all, who would he have had to kill back then?
Do some of the more experienced DMs here have any ideas for me?