Challenge maps

Bloodlust and Executioner are not needed,

I was already using Bloodlust and Executioner out of panic, just to buff the harpy with everything I could. If they aren't needed, that's even better. Although, I noticed that casting Frenzy didn't make sense anymore – the damage from it didn't change, and I didn't have time to check the effects of Bloodlust and Executioner. Besides, it was already night, and I just abandoned that attempt (although, to be honest, I just misclicked. Instead of attacking the dragon with the harpy, I started attacking it with the lich and ruined the attempt). Also, I didn't have much mana left, as the experiments I was conducting during the battle consumed a significant amount of it.
Although, I think Bless would be a good addition there, considering the insane damage output of the harpies. Sometimes they hit for 50-60, and sometimes even for 100 against the dragons. Mostly, though, they hit for around 70-80.

In general, the proposed solutions for the battles are very good, especially against the combination of heroes with Rust Dragons. Victory with almost zero mana spent in the second battle!

I actually thought that this strategy was the author's idea, since they gave us Blindness before the last battle, and we barely had enough mana. :D