MTR 3.16 Sideboard

A sideboard is a group of additional cards the player may use to modify their deck between games of a match. The player may use these cards in their main deck during all games after the first one in a match.

Before each game begins, players must present their sideboard (if any) face down. Opponents may count the number of cards in their opponent’s sideboard at any time. Players are not required to reveal how many cards they have swapped from their main deck to their sideboard and do not have to swap one for one.

Other items (token cards, double-faced card represented in the deck by a substitute card, etc.) should be kept separate from the sideboard during game play.

During a game, players may look at their own sideboard, keeping it clearly distinguishable from other cards at all times. If a player gains control of another player, they may not look at that player’s sideboard, nor may they have that player access their sideboard.

The deck and sideboard must each be returned to their original compositions before the first game of each match.

Restrictions on the composition and use of a sideboard can be found in the deck construction rules for a particular format type.

If a penalty causes a player to lose the first game in a match before that game has begun, or the first game is intentionally drawn before any cards are played, neither player may use cards from their sideboard for the next game in the match.

If players restart a game due to an in-game effect, the composition of their decks must remain the same for the restarted game.

Certain cards refer to “a (card or cards) you own from outside the game.” In tournament play, a card “you own from outside the game” is a card in that player’s sideboard.