Decklists, deck checks and deck problems

A deck problem has three possible homes, and the penalty depends on which one: the list on paper, the deck on the table, or the cards themselves. A list error is a Game Loss, a presentation error is a Warning, and a marked or poorly shuffled deck is a Warning that you fix.

Start with the list. At high OPL (Organized Play Level) players must register their decks, and the head judge may require it at low OPL (TR 401.1 and TR 401.1.a). The list must be a complete, unambiguous record of the Champion Legend, battlefields, Main Deck including the Chosen Champion, Rune Deck and any sideboard (TR 401.2). Once it has been delivered to an official, it can't be changed (TR 401.3). In a constructed event the Main Deck must be exactly 40 cards, with 1 Legend, 12 runes (rule 103.4.a) and exactly 3 battlefields, each with a unique name (TR 402.1), whereas the Core Rules only ask for at least 40 (rule 103.3). A Decklist Error is a list with illegal elements, such as the wrong deck size, cards that are not legal in the format, more than 3 copies of a Main Deck card between deck and sideboard, cards outside the Legend's domain, a Chosen Champion that does not match the Legend, or decks that do not match the list (TR 703.3, TR 703.3.a). It is a Game Loss, and the remedy keeps the change as small as possible: an illegal list is corrected to a legal state with as little change as possible and the deck is made to match it, and if the presented decks are legal but different from the list, the list is changed to match the decks (TR 703.3.b.1 and TR 703.3.b.2). If the cards to correct it cannot be had in time, the head judge can issue a proxy (TR 703.3.b.3).

Next, the deck on the table. At high OPL judges should check decks during the event, at least 10% of them chosen at random, at the start of a round after the decks are presented and before opening hands are drawn, or after the mulligan if play has not begun and hands are kept. A check inside a match earns the match a time extension (TR 411.1, TR 411.2, TR 411.3, TR 411.3.a and TR 411.3.b). A Deck Presentation Error is a Warning for illegal contents when presenting or during play, for example forgetting to restore the deck to its registered state before a match, forgetting to take the Chosen Champion out of the Main Deck (rule 103.3.a.1), or the wrong deck size (TR 703.4 and TR 703.4.a). If the player catches it after opening hands were drawn and it is easy to restore the deck, they restore it. If anyone else catches it after hands were drawn, or if restoring is not possible, it upgrades to a Game Loss (TR 703.4.c.2, TR 703.4.c.3 and TR 703.4.c.4). A missing Chosen Champion found after the first player's turn begins is handled by OPL: at casual OPL the player searches for a legal one, at competitive OPL a judge searches the player's deck and hand for their registered champion, and at professional OPL play proceeds with the zone empty. Leaving it empty on purpose is cheating (TR 703.4.b.1, TR 703.4.b.2 and TR 703.4.b.3).

Finally, the cards. Players are responsible for keeping cards and sleeves unmarked, a marked card being one that can be identified without seeing its face, and sleeved cards are inspected in their sleeves (TR 423.1, TR 423.2 and TR 423.3). Marked Cards is a Warning, and the fix is to replace the sleeves or cards (TR 703.6 and TR 703.6.d.1). Insufficient Randomization is a Warning too, pile shuffling is only a counting method and does not make a deck random (TR 421.3), and a judge can have the deck reshuffled or shuffle it (TR 703.7, TR 703.7.b and TR 703.7.c). Proxies are not allowed at any OPL except an official proxy the head judge issues, and an alter is allowed unless it obscures the name, Might or cost, carries strategic advice, or is offensive (TR 419.2, TR 419.2.a and TR 419.4).