They light up if they are not common cards, you could score a rare gold card!
I haven't bought any potions yet, so I don't really know how to use them. But this is making me wonder if I should buy some and each time I see a blue, or purple light around the card, hit the gold potion button and hope for a rare or epic gold card.
"Ha ha ha.... wishful thinking.
I'm sure if it was that simple,
Everyone would be doing it!"
The Screen shots below show you the card to the left is gonna be rare, Now watch this...
While I was grabbing the pics, I realised when I took a screen shot, it doesn't keep the mouse in the pic. But you can see when I had the mouse over the left card, the blue light surrounding the card
"She's a Goldie, Awesome!"
And a rare card.... just in this case, it happens to be a rare gold. BONUS!
Surely this isn't just happening on my screen though, have any of you noticed this?
If so, have you tried using the gold potions on those cards?
Give it a crack, and let me know,
If it works I'll buy potions too