I challenge you!

example: I'm adding the hero Sarge (commonly known as Axel) to the reserve. In the map settings, in the Heroes section, I check the boxes for the heroes that will be available on the map. In the script, I write:

player = {1, 2, 3, 4... etc.};
for i = 1, length(player) do
  AllowPlayerTavernHero(player[i], 'Sarge', nil);
end;

Yes, you can summon the same hero from the reserve infinitely. Regarding whether you can summon a copy of the hero from the reserve, I'm not sure, but it's easy to figure out logically for tactical scripts, e.g., using StartCombat... He is not summoned onto the map, which means that effectively, there will only be one hero on the global map. (There is DeployReserveHero for summoning from the reserve onto the global map, but it's not needed here)
80 heroes, that's if it's the standard set... I suggest making it simpler: take one hero for each race, name them something like "Garrison Defender," and summon them :). Control their abilities and upgrades through scripts, depending on the difficulty or other factors, such as the day since the start of the game ;) (this option might even be more fun).

Yes, this is all clear. I was talking about having infinitely different heroes (or at least a minimum of 8 for each race), but here, it's the same one (although you can change it with scripts, but there's a second drawback). And most importantly, it shouldn't reduce the number of heroes that can be recruited. That is, even if you make one identical hero for each building, you'll need a minimum of 9 (3 Towers and 6 Outposts) heroes per race out of the possible 8 :confused: And it's easier to do by sacrificing something else, but that seems wrong.
I didn't have time yesterday; I'll check today. If I can, I'll at least make 3 heroes for each race from copies and test them on a map. I always try not to reduce the functionality offered by the developers, so I won't select starting heroes.
You can use companion heroes, but there are some ugly drawbacks again. Also, the regular version shouldn't contain the mod.
And won't StartCombat... lead to the neutralization of the opponent's hero, meaning the opponent will be controlled by the AI, and that's very important? And if you summon a hero onto the map and control him with the editor, we won't be able to choose the castle arena :(


Added 25 minutes ago
I just checked. Copies work ;)
Both with and without a reserve.
Now, there can be a minimum of 8 heroes for each race, and you can add an opponent against each. That's 64 new ones in total. Heh, that's a lot... Considering that each one will need to be given the right upgrades against each race and combined, it could potentially lead to 192 heroes, although some races are similar, and the upgrades will be too ;)
There's the option to upgrade them with scripts, so you can have fewer heroes in the reserve or keep the already upgraded ones in the reserve. And can you give different icons to the hero through scripts?
And how can you make the opponent control a hero and fight on the castle arena without using the castle itself?