Regarding the flying units – doesn't Inferno/Orcs/Goblins each have only one flying unit? So, having one is perfectly normal, in my opinion.
Harpies – what's so complicated? Harpies are harpies, even in Ashan. They lived in caves, pooped on travelers' heads, caught virgins and babies, impaled them on rocks, and ate their flesh. It's the same here. War means meat. That's why they joined. The Nigonians were just lucky; they discovered the harpies before the Dwarves/Goblins did.
It might seem like I'm a very cruel person:(
Anyway, never mind.
P.S. I feel like a creative genius:[U]
Added 1 minute ago
[/U]And yes, the drawings are great, but the throne should be a regular one, not levitating. Slaves are slaves; they should work hard until they're exhausted. A levitating throne... push it, and it'll move... that's not fair;).