I had earned two packs from playing Arena and went to go open them. The first went smoothly but for the second I opened it, clicked on two cards and then my computer freezed. I restarted and found that my pack was gone and I did not find any additional cards that I did not click on or see. So looks like I lost 3 cards :|. Also for theese sort of issues the game could use a ticket system or something of the sort.