Both players must have exactly 12 cards in their Treasure Deck. At the beginning of the Duel, both players' Treasure Decks are shuffled together, then the starting player places face-down the cards they drew on all zones on their side of the field, without looking at the cards. Neither player can check any of face-down Treasure Cards. The starting player can place a face-down treasure card on either Extra Monster Zone they want. The second player does the same afterwards.
The players then start Dueling normally, as if the face-down Treasure Cards were not on the field. When a non-Treausure Card leaves the field, the Treasure Card underneath it is flipped face-up. Treasure Cards have a "star stat" name Medal Number. After a Treasure Card is flipped face-up, every time a card above it leaves the field, its Medal Number is reduced by 1. If a Treasure Card's Value reaches 0, it is sent to the opponent's hand, where it remains revealed at all times, also for the rest of the Duel, it becomes treated as owned by that player. Treasure Cards do not count within the 6 cards limit in the hand. Treasure cards cannot be sent to the Deck, and cannot be banished face-down. They cannot be removed from the field by card effects, and they cannot be placed back on the field once removed.
Precisions regarding Extra Monster Zones: If the Medal Number of a Treasure Card in an Extra Monster reaches 0 because of an effect while there are no cards in neither Extra Monster Zones, that Treasure Card is sent to the hand of the player who made its Medal Number reach 0.
In addition to the standard victory conditions, a player in a Treasure Duel can also automatically win if:
- They have a total of 7 or more Treasure Cards in their hand, Graveyard, and banished Zone. OR
- The total Medal Number of the Treasure Cards in their hand is higher or equal to 13.