What are "marked cards" considered in a tournament?

Marked cards are considered cards that could introduce an unfair advantage in a tournament setting. This occurs when the cards have identifiable characteristics that allow a player to gain additional information about their contents or how the cards will behave in the game. This could be due to physical marks, unusual wear, or specific alterations made to the cards which could alert the player about their identity or the order in which they might appear.

The identification of such cards is crucial for maintaining the integrity of the game, as they can undermine fairness and the spirit of competition. Tournament organizers and judges are vigilant about ensuring that all players compete with decks that are indistinguishable in regard to their capabilities and contents, to uphold a level playing field. Other choices presented do not accurately capture the essence of what constitutes marked cards within the context of tournament rules.