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

In general, a pattern has emerged:

in a battle initiated with Q, if you enable sound effects, attack creatures, and immediately press Q before the sound finishes playing, you will lose.

If you wait for the sound to finish playing, you will win! Moreover, Hydras survive with different numbers: 14, 10, 7, 2. (there may be others, varying)

If you disable sound effects and quickly press Q and start the battle, you will lose.

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This save file continues to surprise me. The funny thing is that there's a Vistan in the tavern, and the situation is completely reversed with him. If you exchange troops and artifacts with him (I didn't take the lizards) and attack with Q without waiting for the sound effect to finish playing, you will win; if you wait, you will lose.