It's round five of an eight round PTQ.  You're 3-1 and pretty confident in your deck's ability to win four matches and get you to the top 8.  So what do you do when...

  1. You draw your opening hand for game one and see a card from your sideboard in your hand?
  2. You mulligan to six cards. Your opponent isn't paying attention and you accidentally draw seven?
  3. In game two of a constructed match, you mulligan to six cards. You pile shuffle your deck and realize that there is one more card in your deck than there should be, and your opponent doesn't notice?
  4. Your opponent is shuffling his deck and several cards from his deck are exposed slightly (you'd have to be focusing on their deck to tell what the cards are) during the shuffle?

Would the action you take depend on the level of tournament you were playing in? Your record and chances of advancing? The prize at the end of the day?