Card Packs can be earned as rewards from completing certain Tiers of each Collection Events, or by purchasing them from the Card Sale Event. The Card Sale Event will appear along the top of your Bingo Lobby just below "EVENTS".

 

You can also earn Card Packs as rewards from:

Tip: Card Collection Events are only available for a limited time, so be sure to check the countdown timer often! Open all your Card Packs before the Event ends as it will not carry over to the next Event.