it doesn't matter; what's important are the resources and ideas. I don't have the resources for a complete Necropolis, so the Necropolis turned into Haven, but that's not the point. Right now, the problem is with the demons – it's unclear what to do with them because there are no ideas for upgrades. The small demon doesn't have any dark elements, the large one lacks a unique feature, and most importantly, there are no ideas about them! That is, when I found the Dragon Skull, I knew what to do – I sat down and did it, but now there's no inspiration.
For the large one, some membranes on the wings and some tattoos or markings on its body would be suitable. Change the glow of both to red and, perhaps, add accessories like chains.