HoMM3 HD is a mod (add-on) for the game Heroes of Might and Magic 3.

...Moreover, after casting Berserk, if artifacts are present, the information in the status bar completely disappears. And even with other various pendants providing magical protection, a message appears stating that you cannot cast that particular spell, but in this case, there is silence. Perhaps, the issue lies somewhere here.

If you cast a spell on an enemy wearing a Charm that protects against Berserk, the AI will not indicate that it has no effect, and the spell will be wasted. To avoid this, enable cursor highlighting in the battle options, select Berserk in the spellbook, and target the enemy unit. If the hex where the unit is standing is not highlighted, your Berserk will not affect it. Then, you can cancel the spell. (p.33 of the Heroes of Might and Magic III Handbook). As for why this happens, it is most likely a bug in the game (similar to the incorrect display of damage in some cases).