[ANNOUNCEMENT] Heroes 3: World Tournament - an add-on for tournament games.

So, what's the point here? Explain it to me. And they made the already dumb AI even weaker by removing the unit's natural ability.

Don't be so harsh in your criticism. The point is that when mana is very important, you can fight in a quick battle without losing it, but there will often be some losses. In other words, variability has been added so that the player can decide for themselves what is more valuable: to possibly incur losses or to conserve mana.