Nigon is the second underground race.

Ar, you need to read the lore. The Dark and the Gnomes even had a war... a long one. They couldn't agree on who controlled the Underground. This is a common theme everywhere. And (I don't know how many times I have to repeat this) – if you're creating a faction for Heroes 5, FORGET about Heroes 3. Then (if the idea itself is good), you can refine the concept. Regarding the Djinns in the armies, I was also annoyed. BUT, the Illithids are associated with D&D. And there, they are different :) + it doesn't fit. There's no OVERALL IDEA. There's just a bunch of mixed creatures :) And how are they connected to each other? Without the Illithids, you could call them the "Alliance of Creatures." Because out of the higher-level creatures, only the Illithids and the intelligent ones are present :) So, you can create a combination of creatures, and an Illithid hero controls them. And that will create a connection.