13га
I am, to put it mildly, somewhat puzzled by your story about completing the map with Zephyr. On the "Hero" difficulty, all the starting packs are completely impossible to complete with Zephyr.
I can only confirm what Gerter and MasteR wrote. Zephyr on "Hero" difficulty eliminates all neutral creatures from the very beginning, with very few exceptions. By the first week, both dwelling of gremlins and both upgrade forts should be cleared. Further progress depends on the player's wishes. I usually captured the gold mine by the end of the week; money is very important for the Knight Castle. The basis of this development is Zephyr's special ability: a killed stack turns into an elemental, which is noticeably stronger than the killed gremlin. Zephyr easily gets Fire Warriors, around level 4-5. Getting an education is also not a problem; if you managed to trade for Logistics, he clears the entire territory like a bulldozer, at the speed of a racing car.
I didn't play the campaign, only this map separately. For strategic gameplay, this map is one of the best. It requires knowledge of the castle economy, plans for their development. Good interaction between heroes, clearly defined tasks for each. And, despite the fact that the player has a large group, there are no useless characters there. The map is fast-paced; it is not suitable for those who like to dawdle before doing anything.