The Fall of Shanti

Or am I wrong, but it seems that the difficulty level only affects battles with neutral creatures.

In this map, the armies of all heroes are scripted, except for Laura's. I configured the Knights as follows: a certain number of troops are given initially, and the rest are proportional to the difficulty level. The army on "Hero" is 2.5 times larger than the army on "Recruit". For Tas'Nelit, the army depends on the week you arrive. On "Recruit," you get 1 weekly army increase, and on "Hero," you get 2.5, and also, only on "Hero" does the number of Black Dragons increase.

The recipe is clear: after taking the human capital, don't rush to free the last member of the Council.

No, there's no need to rush anywhere :). At the beginning of the mission, calmly build your Castle, defeat the Phoenixes to learn Chaos Magic, and recruit Archers. Then everything goes smoothly. I reached the garrison on the fifth week.

By the way, it might be easier on "Hero" than on "Recruit" because there are many more neutral creatures from which you can gain experience, and the hero's stats are crucial in this mission.