I finished my daily quest earlier today. I broke my own rule and bought a quest potion to get additional cards since the chance of getting a card is 50%. I opened six chests and got 1 card. Granted it was a rare one so covered the DEC cost to purchase the potion if you look at the USD value however the DEC value is only 20. I say I am lucky to get a card.

My strategy is to get as many cards as possible and level them up to as high as I can.