From Arcane Wonders:
As Supreme Commander of your country’s military forces, you must carefully deploy your forces across three possible theaters of war: Air, Land, and Sea. The order you play your Battle cards is critical, and so is how you play them. All cards can either be played face-up or face-down. Playing a card face-up triggers its Tactical Ability, but the card must be played in its corresponding theater. Face-down cards are wild and can be played to any theater, but they only have a strength of 2 and do not grant Tactical Abilities.
At the start of each battle, you will be dealt a hand of six cards. You will not draw additional cards during the Battle, so you must formulate your strategy based on only these cards. Players take turns playing Battle cards one at a time, until either all cards have been played or one player decides to withdraw.
You do not have to continue a Battle to the very end. Sometimes, it may be best to withdraw in order to deny your opponent complete victory! In Air, Land, & Sea, a strategic withdrawal may lose you the battle to ultimately win the war! Victory points are awarded at the end of each Battle based on the results, and the first player to 12 victory points wins the war!
