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I elaborated on this in the regulations, based on the questions raised:
When playing on the SoD version of Heroes, the "guild hall reconstruction" option must be enabled on all tournament maps except Anarchy.
Players are prohibited from building a Library in any city on the map except for the starting city of the Tower, from which one of the players starts.
If a player captures the Tower city, in which the Library was built by the AI, they can use it without any restrictions.
In other words, answering the questions of Dirty and Gomunguls, a player who did not start with the Tower, having captured the starting Tower from their opponent, has the right to both build a Library in this city and rebuild the Guild Hall with an already built Library.
Also, a second clarification has been added, stating that if the AI builds a Library in any other Tower on the map, then after capturing such a city, the Library can be used and the Guild Hall can be rebuilt.