Thus sites which host MWS limited tournaments make players build their decks online, and use a security code which will change with any contents of the deck. This precaution helps prevent any dishonest play in a limited game, so long as both players ensure that their opponent's code is valid.
This approach enables sites hosting MWS limited tournaments to ensure fair play by requiring players to use a changing security code tied to their deck's contents. Both players must verify their opponent's code to prevent cheating in limited games.