Uninvited guests.

I played the next "hero" – a mage – for 174 days. Astrid turned out to be a decent hero, no worse than the standard ones from the Castle. To my surprise, Astrid had an easy time, even though the Castle is very difficult to play. It requires a huge amount of resources, and of all kinds. I hardly thought about the mini-arts until the very end of the game. When the time came and a horde of enemies surrounded the Castle on the second week, I was ready to surrender quietly. There was almost no army, and the magic power was negligible. But something incredible happened: all the AI heroes ran past, chasing Hafiz (with one gremlin). By maneuvering skillfully, he destroyed 4 heroes, or rather, they fought for the right to catch him. Two more went to the far reaches. Hafiz "held back" the AI's onslaught for almost a month before he died. The first time the Castle was attacked by a minor demon, right after the first destruction of the Castle; I barely defeated him. Again, I got lucky; a bag of artifacts dropped from him, which he didn't manage to carry to his hero (he ran around "naked" until the end of the game). After that, there was calm again. Astrid frantically cleared out various mines scattered across the map, leaving the Castle empty, and no one was interested in it. After the second destruction of the Castle, finally, an AI hero attacked. Before that, he had defeated the AI gnome hero. Astrid's battle with the necromancer went smoothly. All the spells were reflected, and the troops couldn't break through the walls. My hero developed to level 29, and it became easy to play. The demon captured the gnome Castle and killed everyone. Astrid didn't encounter a single gnome during the game. The necromancer AI took the Necropolis Castle, blocking himself there for a long time with an oncoming caravan. Since war elephants were not available, it became more difficult to capture enemy cities and return to my own.

During the game, I looked for the witches' coven, and then abandoned it because it was no longer needed (if the destruction is critical at the beginning of the game, then by the middle of the game it is easily overcome).

I completely agree with the comment. I know where the witches' coven is located, but there is no need to go there. The first destruction of the Castle is scary. After that, it's easier to capture an enemy city where a capitol and a tower have already been built than to go looking for witches (yes, and it's so far away). It would be better to move the witches' coven to a more accessible location, and make the destruction of the Castle increase gradually: from small to almost complete destruction.