The Sun Lich

 This is a campaign setting idea I've had for years but never got to use.  Perhaps you can have fun with it?

Edge of Darkness by Ben J

Long ago, a world was destroyed... mostly. A very powerful lich needed that world, and saved a portion of it. This chunk of planet (so this is now a "flat" world with an edge") drifts into space. The magic of the lich keeps the air in place. But the sun is gone. So the lich, grown to titanic size, uses a glowing gem on the tip of their staff and moves it in a circle around the world, mimicking the sun, giving it... life.

During the daytime, the light of the staff, much like the sun, makes it very hard to see into space.  But at night, when the staff is underneath the world, the lich is faintly visible, illuminated from bellow.  (Midnight is known as "the ribbing hour" as the angle makes some features more apparent).

The main religion of this world worships the lich as a sun god, and offer sacrifice, thus powering the lich.  Faithful elders often choose to end their lives this way.  

Thus, centuries pass, with the sun staff going round and round around the broken world; while the lich drifts in the cosmos, pondering its next move.  But what if things changed?  

Perhaps the lich is now ready for the next step of its plan, but demands far greater sacrifices to give itself the power to do so. 

Perhaps a heretical sect claims the lich was responsible for the destruction of the world, and only preserved a portion of it so it may use the inhabitants as fuel.  Perhaps these ideas originated from visitors from beyond this world. 

Perhaps the population doesn't know that the end of life ritual consumes the soul of the sacrificed - what if this dark secret got out?

Perhaps this is just background, a backdrop to whatever great idea you have for a campaign?