Are players required to deck check their opponent's list before playing the first round, and how can they detect violations like pre-siding?

Ruling: Players are not required to deck check the opponent's list as it is private knowledge. However, players are required to verify the overall construction is correct (1 Legend, 1 CC, 39 Main, 12 Runes, 3 BF) and legal.

Sequence:

• Players may request a judge to do a deck check on their opponent at an appropriate time
• This should only be used if there are reasons to suspect the opponent might have altered their deck
• Players must inform judges of any problems as soon as they occur or are noticed

Nuances:

• If a judge determines you purposefully avoided informing them of a deck list error to gain an advantage, you can be penalized
• Examples of suspicious situations include: opponent starting with a non-standard chosen champion that has a good matchup, or playing cards game 1 that should only be sideboard options
• For big tournaments, deck lists become practically open for top cut as they're shown before matches start
• Event organizers are required to deck check 10% randomly per round