The Joker is a special card that gives you the option to earn any card missing from your album! 
One Joker gives you one card.
There are three types of Jokers
:
Four Stars Joker
Five Stars Joker
Ace Joker
The Joker type determines which card it can replace.
You can complete quests and trade duplicates to win Joker Cards.
Keep your eye out- Joker cards can be offered in daily offers 
* Each Joker Card can turn into a card on the same level. For example, a 4-Star Joker can only turn into a 4-Star card.
* Please note that when you have all the cards that the Joker can provide in an album, any additional Joker you have automatically turn into a sum of duplicates.
* But time is ticking
Joker cards have an expiration date, so make sure to use them before they expire!