Light of Avanor
All of Avanor is covered in perpetual darkness that has exsisted since the fall of the Golden Sun Empire.
The event is referred to often as the [["Black Viel"]], referring to the fact the islands are called sisters.
Though the exact reason for the darkness remains unknown what is known is that it occured as the last King of the Golden Sun Empire died.
Efforts have been made to try and permanently remove the darkness through magical and divine methods, however none have worked thus far. While momentarily the darkness can be held at bay the light source is removed the darkness returns.
The current most common method of holding the darkness at bay is through lamps. Each major settlement has a larger lamp, while invidual smaller portable lamps are often given to adventurers and various military patrols.