So, under normal circumstances.
In a world like this one, before the Black Prison Race decides to harvest the entire world.
The surface world typically only allows clans of the Black Prison Race in their larval stage to operate. They survive by parasitizing hosts, constantly migrating to grow.
As for the Entry Tier Black Prison Race members?
Although they don't seem to be allowed on the surface during normal times.
But whenever wars of varying scales break out on the borders of the various Kingdoms, or even between certain factions...
this restriction is lifted!
Because battlefields are where negative energy is most concentrated.
When soldiers die, their unwillingness, resentment, terror, fear, and anger all intertwine. This can generate an amount of negative energy that far exceeds the total a normal human could ever produce in peacetime.
