Who has enough powerful magic.

1. When fighting fast units (like nightmares, lizards), you need larger creatures and to hide them behind various obstacles, but if there are none and you don't want to lose troops, do not deploy them for battle at all.
2. For me, the main thing is initiative; therefore, you should take more corresponding troops into your army, and if there are few of those, apply a general slow on the enemy.
3. When attacking shooters, do not expose your own troops to point-blank shots.

In a game against the computer, this is all correct, but against an equal opponent, various tactics are necessary, depending primarily on which race you are facing and the characteristics of the opponent, which can often be better than yours; with the computer this works, with a human it's not guaranteed. Therefore, the main thing is to develop yourself and prevent the other from developing, and before the battle with the main forces, send a level-6 hero at the opponent to remove positive effects from them.