Balance in Heroes 5.

Distraction – and your magic slows down its development; readiness – and with one hit from a Phoenix, it gets two free attacks. And if the Dwarf is lucky with exorcism, your Phoenix won't live long.

I'm about to start laughing... A Dwarf with a build focused on sorcery, defense, chaos, and summoning... That's something else. But I don't care about such a Dwarf, whether he's in a Castle or in the field. He won't be able to do anything. And exorcism is cool, of course, but in the hands of a Warlock with arcane and sorcery luck, while the Dwarf will get tired of poking at the Phoenix.
And about the Tower. So what if they're summoned? Pure defense can't do anything on its own. Accordingly, the longer the game lasts, the less useful it becomes. No matter how it seems to be the opposite. Simply, if a Dwarf in a long game fortifies himself in a Castle for the final battle, it means he's already weaker in terms of power, and that's a disaster, and no Tower will help here. And even more so, they are not cheaters with a Tower; this has been repeatedly proven online by many players.

And when I said about the weakness of the dark elves, I meant that in the final battle, the coolest thing is to use combinations of Hydras and girls with glowing swords, along with dinosaur riders and their lizard-bite. The problem is that the latter pair can't take a hit and dies at the speed of an electron emitted from a synchrophasotron emitter, and that's their main problem.

In the final battle, the coolest thing is the hero and his magic; all these lizards and, even more so, furies are just to distract the enemy for one attack. The basis is Hydras, Minotaurs, and Assassins, due to their incredible resilience, and at the head of it all is the HERO. And if the main problem for you is the weakness of the army, then the problem is solved by deleting the krivie_ryki.sys file.