"But what about invulnerability to darkness and targeted spells?" - Does it mean you absolutely have to cast them? Besides, this invulnerability lasts only 3 turns.

And it doesn't necessarily have to be cast on them specifically, because mass slow and other similar mass darkness spells will automatically affect everyone, but not the witches, thanks to invisibility. And 3 turns may seem like a short time when fighting neutrals, but in the endgame, it's a lot.

Well, that's just your case, not an axiom. Maybe someone else, with different troops and stat distribution, would have saved a turn by gathering all the troops.

The key word is "maybe." Anything is possible, but I've definitely verified what I wrote.

It always seemed to me that at the beginning, everyone tries to eliminate as many archers as possible, but since there are no archers in this situation... the riders will be caught in the fray anyway. And if the magic is good, why should they run to the other side of the field? Just stand there and enjoy watching the nightmares, along with the succubi and devils, decay under the meteor shower.

Actually, archers are not popular in the Dungeon faction for some reason. Apparently, their damage is too low. Compare the damage of the riders charging and the shot of the Sovereigns. There's no need to think about who to eliminate first. And they will still have to run, because if the battle is with a demon, where are you going to get mana if the imps steal it? And even if it's not a demon, everyone understands that you can't delay with the Dungeon faction; you need to attack immediately. And in this case, the riders might not be lucky if they end up facing paladins, for example. No, if you want to get the most out of them on the battlefield, you need to run without thinking. Otherwise, there will be no one left to run later.

"But the biggest imbalance is the Battle to the Death" - Battle to the Death... please explain.

The question is not for me, but I will explain: Battle to the Death, also known as БДП.

"Invisibility is an imbalance, especially if there are more than 450 Stalkers and more than 45 Matriarchs" - What's going on with the enemy then?

Yes, at this stage of the game, the Dungeon faction cannot win with invisibility or chaos. You definitely shouldn't bring the game to this point