NightWing island

The Night Kingdom is the kingdom of the NightWings. There is a portal to it in the Rainforest Kingdom.

It is located on an island or other landmass, covered in volcanoes and lava. There is thick smog over it, most likely from the eruptions. The entire land is dark due to the clouds of sulfur, smoke, and debris. There is black stone fortresses, where the NightWings live. There is also small cells for prisoners and RainWings that they capture.