I tried my hand at making a new magic site. Actually, I might eventually make this into a full nation, but I don't have time ATM. Any way, from Castle Wyvern you can recruit Wyvern Knights and Wyvern Lords, elite soldiers keeping peace around their mountain (which doesn't actually have a fortress).
Unfortunately, because we don't have commands for non-capital-only recruitables from magic sites, this mod doesn't really work. So I gave up and gave the site to MA Agartha. It doesn't fit the nation, at all.
