25-7-12 Regarding Invitation Bonus Card
From Rage of Bahamut WIKI
The Invitation Bonus Card you will receive will be the card that is in promotion at the time your friend enters your Referral Code. You will get the Invitation Bonus Card when your friend reaches level 10. The card you will receive might be different from the card displayed in the game at the time you send out your Refferal Code.
Rage of Bahamut Management Office.