Atm with the pack im designing the default world is BetweenLands, but id also like to have some of the mobs if not all available to naturally spawn in that dimension if possible.

I would have it at a guess it dose not use the BiomeDictionary at all, but i appreciate the feedback and will see if there is a way to force spawn them or re-think starting dim.

Wait, you want mobs to spawn in a dimension? That is a first for me. Players usually complain about the mobs spawning in a dimension, not the other way around.

Unfortunately that is currently not possible. The mobs use the BiomeDictionary to spawn. If they are currently not spawning in the BetweenLands biome that means the dimension must be using a unique combination of BiomeDictionary entries or not use it at all.

It uses the biomedictionary. But currently (1.12.2) it only iterates through the vanilla biomes I believe.

In 1.13 I iterate through the Forge biome registry

Can this be fixed so that we can use InControl to control mob spawning per dimension?