Heroes of Might and Magic IV “King of the Hill” Duel Tournament

It will work, but the berserk effect won't disappear until the Phoenix actually attacks someone. So, I still insist that resistance to berserk is the key here.

That's quite strange. Hive Mind affects enemy units. Exorcism only affects your own units. It turns out that under the berserk effect, the unit belongs to both sides. Although the same happens with hypnosis. But Zybr is right, berserk doesn't always last for just one turn. It lasts until the first attack of the berserker, i.e., the duration of this spell ranges from 1 turn to the end of the battle. A constant Hive Mind disables the Phoenix for the entire game.