it's not mercs, I have seen a dragon knight coming out of a mino arena, it's (likely) not a quest reward, I witnessed minos with empire troops/buildings/builders and orcs going crazy on D.Dwarf buildings
Is it an alliance thing? A quest reward? Or..tldr...bug or feature?
thanks
Edit: scratch the alliance thing, except empire has a secret alliance with the demons
Edit2: nvm, it's a faction thing...how cool is that?