Ever since the Christmas update, there's a calendar where you collect coins, hearts, gems, and cards. And at the end, you get a random Gold Card.
You can even get Christmas cards on the Adventure Calendar! You can get a Snowball, a Candy Igloo, or a Rainbow Gnome. And you can get Holiday Keys to get Christmas Jake (Hero Card) and Christmas BMO!!!
On days 1,4,7,10,13,16,19, and 22, you'll get 10000 coins. On days 2,5,8,11,14,17,20 and 23, you'll get 5 hearts. On days 3,9,15, and 21, you'll get 1 gem. On days 6,12,18 and 24, you'll get 1 normal card, and on day 25 you will get 1 Gold Card.