What must players do if they need to replace a card in their deck during a match?

When players need to replace a card in their deck during a match, the correct course of action is to inform the judge before making any changes. This requirement is in place to maintain the integrity of the game and ensure that all players adhere to the rules and protocols established for tournament play.

Notifying the judge is crucial because card replacement can impact the game state, and it's essential that the tournament officials are aware of any changes made to a player's deck. This helps prevent misunderstandings or potential issues arising from unauthorized changes.

Each of the other options suggests actions that do not align with the rules governing the integrity of matches. For instance, replacing cards without notifying anyone overlooks the necessity of maintaining transparency during gameplay. Similarly, only replacing cards after winning a match or limiting replacements to cards of lesser value restricts a player's ability to properly manage their deck without valid justification. Such restrictions would not be fair or reasonable under the competitive rules established in sanctioned play.