I did get used to get 5 extra chests per day. During the past 115 days this was the case, thanks to a $70 investment I was able to purchase 100 potion quests and got an extra 15 for free.
Now this same amount of potion quests would cost me 70500 DEC, or around $600. That is a huge difference, so wont do that again.
I did made a huge profit on that $70 investment, but I doubt it that this would also be the case if you do have to invest $600.

The daily!

Had to be battled out with the death element and went surprisingly smooth. Only had to battle 7 times to complete the quest.
And the rewards were superb with a legendary, an epic and a rare card!

Cheers,
Peter