Nigon is the second underground race.

Come on, why stick to a template? If there's an original idea for a unit, but it doesn't fit the overall concept (like requiring a flying unit, and if it's the only one, it has to be at least level 6), then forget about it. Create the unit, and you'll be happy. The thing is, the Ifrit is cool and fits, and the Harpy is a flying unit)
So, in principle, the discussion is pointless.

I agree)) I'm not the only one who thinks Ifrits fit the theme)) And if others don't like it, there's nothing I can do about it)))
In Heroes 4, they weren't with the Demons, but with Chaos, along with Medusas, Minotaurs, and Black Dragons. It was unusual, but we got used to it! So, everything is fine here)))
P.S. And Chaos was the most diverse faction. There were creatures from all sorts of factions)