The attacking Kingdom should have to break down the doors of the defending kingdoms Castle and slay their Empress/King/Gov/Dictatress
Defending Kingdom could set up forts around their castle to make the attack harder or could attempt to kill the attackers before their assualt is mounted.
Just a suggestion, but basically the game needs war rules and War Admins to make sure rules are followed.
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Also no Earth to Dust during wars, but other magic is no problem.