He'll take a look at their cards, checking features like the borders, to make sure the image on the card is perfectly centered, and ensuring there are no printing imperfections
This game brought many mechanics that arent present in the original trading card game, and if that wasnt enough, it also nerfed all effect monster cards to the point where all monster cards had no effects or abilities
Yamagata Prefecture is up against the Sea of Japan, in the southern part of the Tohoku region, and it's especially popular in winter, when travelers soak in the onsen (hot springs) and ski down snowy slopes
You can think of it as a mental strength version of a medical book
Adding to the mystery, Mike would willingly show the card to some players late in the evening, after the main events had shut down and been packed up