I have not seen the Daily Crystal Boosters so I have asked EA by Chat,e-mails, etc. and it is still in progress.
Recently, I found that was meaningless.
In order to figure it out, I made a new Game Center ID and logged on the game then I was shocked.
At the Arena of New ID, just Lv28 is #1 and the #1 is the only 4* leader. Lv 10,15, even 8 is under #10 or 20.
They have got #1 or high ranked reward everyday which is much more than the Daily Crystal and grown Dath~ character much faster.
I spent much money, power is about 11000, but just stay in #150~#300 and get a reward just as it.
I have spent much time asking EA how to pay for the invisible Daily Crystal which is much smaller than their everyday reward.
I feel I was just stupid.
Is it fair?
(I have the screenshot but this website does not allow to attch a file.)