It's a mini-activity available during the Card Collection Activity meant to help you get more free Cards. You will get points in Time-Limited Fun based on the number and the star rating of the Card Packs you open. The more Card Packs you open and the higher their star rating is, the more free Card Packs you will get. We recommend that you check the time of this mini-activity before opening a Card Pack. The exact time can be found in the fourth tab on the left side of the activity page。