During a standard constructed Pro Tour Qualifier, Adam is deck checked during round 3, and is found to have the following cards listed as their sideboard:

4 Cancel
4 Flashfreeze
4 Phyrexian Revoker
4 Garruk, Primal Hunter

What is the appropriate infraction, penalty, and additional fix, if any?

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The definition of deck/decklist problem is as follows:

This decklist has 16 cards in the sideboard, which is too many! Assuming all the cards are legal for the format then the MIPG has a specific fix:

If the deck and decklist both violate a maximum cards restriction (usually too many cards in a sideboard or more than four of a card), remove cards starting from the bottom of the appropriate section of the list.

This means we remove the bottom sideboard card and then alter the list. The player then gets a game loss and can continue playing!

What this means for us is that our deck list should now look like:

4 Cancel
4 Flashfreeze
4 Phyrexian Revoker
3 Garruk, Primal Hunter

We also alter the deck list to accurately reflect our new sideboard.

Note that there was another possibility here: As a special bonus, let’s play “what-if”!

What would we do if the player is playing 15 cards in their sideboard?

If that is the case then we apply the fix:

Remove any cards from the deck that are illegal for the format or violate the maximum number allowed, fix any failures to de-sideboard, restore any missing cards if they (or identical replacements) can be located, then alter the decklist to reflect the remaining deck.

Notice that we do not have to remove any cards! We simply issue the game loss and alter the decklist. The player then gets to happily continue playing!
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