In 1.3.1, a bug no doubt as it is written in Russian, if you mouse over your Defense, you can see the number of Counter Attacks you have remaining. Naturally, this also means you have the ability to Counter Attack.
So, you can check which units can counter-attack during battle.
By the way, while casting berserk on your Horsemen is nice, I like how counter-attack works on...
Ogres, Orc Chieftains, and Trolls. I just finished the game using those 3 guys are mega monsters in the mid-late game along with Black Dragons and Rune Mages.
Ogre with ogre rage avoids the need to spend time on berserker.
