First let me say: it's a great game! I have been playing for 3 days and really love it! And I got a few questions: 1.When can I get bonus for inviting a friend to play? I already invited 15 of them to join me and some of them have level up their ranks but I don't get any crystal yet. :( 2.I will get the bonus just one time for each person or I can get more and more as their ranks getting higher everytime? 3.What the the battle bank means? Don't know how to use it. 4.Can I buy crystal by Asian countries credit card cause I don't have paypal. Thanks a lot!