A simple fix for duplicate cards
when a player opens a pack of cards have the code look at the cards the player library and assign a value to each card the player has mastered equal to the value of a rare, thus greatly reducing the chances of pulling a duplicate.
this will encourage players to master more cards and move them up the ranks
I have pulled way to many haunted cloaks and i would gladly master this if it meant never having to see in in a pack again
I am positive someone smarter than me could expand on this but its way better than the current system