And here, what seems like a useless wall of fire in a battle against a human, actually isn't needed at all, but it leveled up the hero without much effort and took resources from the poor monsters, which, for example, on the first week, were used to build a level 7 unit in the Castle. That's how it is.

And here, Solmyr's chain lightning also helps in leveling up, and unlike the wall of fire, it will be useful in a battle against a human.

I'm fighting. After all, a group of angels and ducks will defeat anyone by the 3rd week, even without a wall of fire, right? ;)

Even if you capture all the mines in the first week, by the third week you will have a maximum of 10 ducks (are you talking about Firebirds, am I right?), but there will be few of the other units, because there will be a shortage of money. And where will you get a group of angels by the third week? Unless you get lucky and stumble upon the Griffin Conservatory, but it will still be difficult to storm. Option 2 - you find a Castle, but again, there won't be enough money to build it up to the point of having Angels.

Added 1 minute ago
Oh! It just occurred to me that you're talking about playing as the Castle, and the ducks are Griffins. But then a logical question arises - how will you have a hero named Luna if you're not playing as the Conflux, because the chance of finding it in the tavern is extremely small?