A detailed explanation of how the spawn mechanic works
As one of our targets was to maintain a natural spawning and not a sudden surprise mob spawning behind you, we came up with a solution that would maintain natural mob spawning but with additional custom mobs included.
We came up with the solution to replace mobs that are spawned by Minecraft with our custom mobs. When a mob is spawning, an extended flow of conditions will execute. Based on the outcome of the condition, we might replace the original mob with a custom mob or keep the mob that was originally spawned.
Every custom mob that is spawned will be registered on the blood-moon. Whenever the blood-moon ends, all the custom mobs will automatically despawn.
The custom mob spawning allows the plugin to spawn mobs in a radius around the player with a given minimum and maximum radius. Mob spawning does completely ignore natural spawning and therefore it will also spawn mobs in places that have high light levels.
The server administrator can configure the maximum amount of mobs within a single chunk. By default, this feature is disabled.