Hi! Thank you for purchasing the asset! Well, the easiest way it comes to my mind right now is to have a hand[] array (or ds_list) which stores the instance IDs of the cards being drawn, and a index counter variable. So that when you press the button “>” the index variable increases by one and when you press the “<“ it decreases.
Then when you want to play a card (“A” being pressed) you check which card is currently selected by retrieving the ID from hand[index].
Let me know if that can help you.