Congrats on making it to Gold III. I made it to that level as well. They brought out new rewards cards which is why you are only just seeing them.
Furious Chicken is a cool card. When combining cards, what I do is only use enough cards to get to the next level. This is so that the spare cards can still be accessed if I need to sell them. It's no big deal but what happens is that those cards can sometimes become very expensive to get to the next level.
So, now I keep some uncombined. In the future people will want to rent the individual cards when they become rare.
It's also important to improve your summoners as much as possible.

Thank you for bringing the Christmas spirit back to DTube.