I see several ways to abuse this feature in the final stage of the game by the defending player.

It would be worth listing them. For now, I only see abusing blindness/berserk/hypnosis on a hero with a lot of spell points/mana, but without an army. The defending player blinds/... the attacking player until they have to retreat/bribe. But it doesn't seem like something that is impossible to protect against, especially since the attacker chooses the formation, and heroes with mana are dangerous anyway.

And what's wrong with the simple option that there is always snow in the workshops?
and golems accordingly run with +1 speed.

It was mentioned above. Most likely, they will come up with a way to take it, even for this option. If you can prove that this is impossible, it would be interesting to hear.