Apparently, this “Star Nest” was produced when a Star Cultivator and a Star Maiden contracted with one another, and it was akin to a sort of “astral” space. This sort of space was opened by each other’s Astral Crests, and the Star Generals that sign contracts are able to retreat to the Star Nest to recover. Because Star Generals are unable to cultivate Star Energy, they therefore enter the Star Nest to share the Star Energy of their Master in order to grow their own. And this is one reason why Star Generals sign Star Duel Covenants with Star Masters.
Only by doing so can the Earthly Fiends’ Star Energy exceed the most powerful Heavenly Spirits.
Signing the Star Duel Covenant doesn’t only mean that every other Star General is an enemy. It’s those cultivators that are the biggest threat. Ordering a Star General into the Star Nest is a great way to hide people from prying eyes. It hides their identity, otherwise, you’d die a hundred time before even reaching Maiden Mountain.