You would have to call your bank and see if the debit card can act as a credit card under a major credit card company. You can look at yourself and see if it has a major credit card company's logo and the banking logo on it.

Instances in FINAL FANTASY XI are called Burning Circle Notorious Monsters. Players gather at a specific point typically located at the ends of dangerous dungeons and use that circle to enter a battlefield where they engage with a powerful monster. It is a boss battle. Rewards may vary.