Let’s come up with new “war machines.”

That's clearly an overdoing. It's better to have unique items for each faction than just generic siege weapons and towers, which, by the way, don't really fit the style of Heroes.

P.S.: Could it be possible to make it so that a hero with the advanced ballistics skill has the option to buy not just a tent, a ballista, and a cart, but two ballistas or two tents. And with expert ballistics - three ballistas or three tents...