How can players verify the legality of their decks before a tournament?

Using resources like the official Magic website is the most reliable method for players to verify the legality of their decks before a tournament. The official website provides up-to-date information on the current tournament rules, banned and restricted lists, and format legality, ensuring that players can check their decks against the most authoritative sources available. By consulting these resources, players can be confident that they are adhering to the most recent and accurate guidelines governing deck construction in their chosen format.

While asking friends may provide some insight, the information might not always be accurate or current. Consulting with opponents, while potentially useful in casual settings, does not guarantee reliable information about deck legality. Relying solely on memory is the least advisable option, as it can lead to misunderstandings about card legality and format restrictions, potentially putting a player at a disadvantage or leading to penalties during the tournament.