Current questions and answers regarding the map editor.

Either way, the hero fights.

Great.

You can read about and download the AI mod here.

I don't know, this topic isn't about the mega AI mod. Here's a link to the forum, you'll find it in the list => https://heroes.ag.ru/heroes5/mods/index.html

Do you need to fill in the function body?

No, if there's no need to, i.e., if there's nothing else in the daily function.
That's correct, there can only be one NEW_DAY_TRIGGER in the script, so just copy this line into your existing function.

Added 2 minutes later
At the right moment
SetObjectOwner(nTownname, 3);
And then do everything as described above to immobilize the AI.

Added 2 minutes later

I understand the idea... but then the town and hero will be messed up. Maybe it's possible to block the entire line? (you could accidentally turn off the AI at the start... I've attached a screenshot)

In Multiplayer, turning off the AI seems to be an unkillable option. I don't understand what "entire line" you want to block?