Open, Pass
Used as Main Match of Season 1, Round 7.
Rules
Each player receives a deck of 20 cards, numbered 0-9 along with mathematical operations +, -, ×, ÷. They may spend garnets to buy additional cards from three decks: black, red, and blue, worth 1, 2, 3 garnets each, and have increasingly better cards. (For example, the black number cards are two copies of 0-3 and one copy of 7-8, while the blue number cards are three copies of 7-9 and one copy of 10. Also, black operation cards have three of subtraction and division, with two of the others, while blue operation cards invert this, having three additions and multiplications and two of the others.)
After buying cards and exchanging with other players if necessary, each player constructs a 20-card deck, which will be shuffled by the dealer. A player may ask for a reshuffle for at most three times. After a player is satisfied with their lay, the dealer begins filling a 10-slot expression with the deck. Each time, a card is placed face down at the rightmost empty space. The player may choose either to open the card, thus opening it and fixing its position, or pass the card, throwing it away without seeing its value. After ten opens (and thus at most ten passes), the expression is created. Only the leftmost number is kept across a stretch of numbers, and similarly with operations. After that, if the rightmost card in the expression is an operation, it is discarded, and if the leftmost card is an operation, a zero is appended to the left of the expression. The result is then evaluated and becomes the score. For example, -, 8, 5, 7, +, ×, 3, ÷, 5, + is converted into 0 – 8 + 3 ÷ 5 = -7.4. The winner is the person with the highest score.