When adding a warg mount to a unit in the unit designer it indicates that it requires a horse resource to make. This should probably be a warg resource. With 25 warg resources I was not able to buy a warg enabled unit. So it does indeed appear to require a horse unit. From what I can tell playing empire there are no horse tiles that I have found.
The game I'm playing now has horses, but I can't make use of the resource, it says my faction can't use that resource. So I COULD have horses, but I can't make use of them. I also had 12 wargs, couldn't build them. It makes it tough to play with empire because it's alot more limited than the kingdoms are. Although it's better than it was in 3A and 3B.
