What must a player do every time their life total changes?

When a player's life total changes during a game, they are required to make a verbal announcement of the new total. This is essential for maintaining transparency and clarity in the game, ensuring both players are fully aware of the current state of play. It helps prevent any misunderstandings or disputes about life totals, which can significantly impact gameplay and strategy. By announcing the new total, the player validates the game state to their opponent and reinforces a mutual understanding, which is a fundamental aspect of competitive play.

The other options do not meet the necessary standard for communication in a Magic: The Gathering game. Simply notifying an opponent silently does not ensure clarity, while writing down the total without announcing it does not provide the same level of awareness. Ignoring minor changes could lead to confusion, especially if the change compounds over multiple turns or interactions. Therefore, verbally declaring the new life total is crucial for effective communication and adherence to tournament rules.