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Question about “Cities & Knights” Expansion Barbarians III: Players are Defeated - If the player with the lowest strength of knights can’t lose a city, who loses one?

Answer

If the player with the lowest strength of knights can’t lose a city, the player with the second lowest strength of knights loses one. If this player can’t lose a city either, the player with the third lowest strength of knights loses one. And so on, until a player has lost a city.