If a player registers a legal decklist but it doesn't match what they intend to play (e.g., wrong chosen champion), can they alter the decklist or must they change their deck to match the list?

Ruling: The deck must be changed to match the registered decklist. The decklist cannot be altered if it is legal, even if it doesn't match what the player intended to play.

Sequence:

• If discovered and the correct cards are easily accessible (in backpack, etc.), the player receives a Warning and must swap to match the decklist
• If the cards cannot be acquired in a timely manner (not easily fixable), the penalty is upgraded to Game Loss
• The head judge CAN issue a proxy if needed to match the decklist, but this is discretionary ("can" not "must")
• The decklist itself is not changed

Nuances:

• If caught before Round 1 starts, judges may allow changing the decklist with no penalty or minimal penalty (judge discretion)
• Once Round 1 begins, the decklist is locked and the deck must match it
• Judges are unlikely to issue proxies for cards the player simply doesn't own or forgot at home
• The Decklist Error infraction (703.3) only applies to illegal decklists; a legal but unintended decklist falls under Deck Presentation Error (703.4)
• If the same issue occurs twice in one tournament, it may result in disqualification for cheating