That thing

go to biomes > and click add biome, you can also rename it if you want

you can adjust the height of the biome by going back to terrain and adding whatever you want to the new biome folder you’ve created, also make sure that the hide empty is turned off

@StarDominatorIIVV Its biome folder i think, you can make it if you make new biome

@SamTheFox i mean the thing with that name

make them like clouds, but they’re polar clouds, and their intensity is significant (intensity changes the glow-in-the-dark-ness while emission determines whether or not shadows affect it’s visibility)