The Legacy of Serrane faction ability has an issue.

It is currently set to block the two normal horses, and unlock another version of a horse called Warhorse.

However, the Warhorse will not appear in the city shop, nor will the other two mounts. Ironically, this leaves the "horse faction" without horses for heroes.

The reason is because the Warhorse is not fulfilling the requirements to show up in a city shop. To show up in a city shop, one out of two requirements must be ful-filled: 1) It must be unlocked by a technology or 2) It must be specifically called from a <CityHub> with <UnlocksShopItem> tag.

In order to make the Warhorse show up in the city shop, please add a technology prerequisite to it like normal horses have.

If your intent is to have the horse available from the start without requiring research, you can automatically unlock a hidden technology for the player through the faction ability instead. It is an ugly solution but it works.