I have added 20 new cards to the game! And you can ONLY unlock them in December!

The card you can unlock is the Christmas tree. You can upgrade the Christmas tree into a stronger version, by collecting three copies of it, just like any other card. And like other cards, it has 5 tiers.

When you play the Christmas card, it will shuffle a random present card in both decks. (One for you, one for your opponent.) The presents are always of the same tier as the Christmas tree that they came from. 

A legendary Christmas tree by itself is not powerful at all, but the presents they shuffle into the decks are much stronger than presents coming from an uncommon deck.


How to obtain the Christmas Card:

There are 3 ways to obtain the card.

1. Visit the Christmas Tree in the mansion.
2. Play once every day, unlock more cards the more often you play in December.
3. Copy your cards at any in-game computer.

The cards are only available in December. 
Januari 1st, is second past midnight, you can not obtain any Christmas Cards any more. This mean, you won't be able to upgrade them either. 
No worries... December 1st next year, the event will be back!