Hi,
Attacking happens after the key is found. When someone lands on a space that is already occupied by someone else they enter into battle. This is when you would use ATK if attacking and DEF if defending. We like to hide all our items and flip at the same time, that way no one knows who is using what. It is up to whoever is playing as long as everyone does the same thing. Some people play that the attacking player has to show the weapon first.
Let me know if you have any other questions.
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