It's highly recommended that you practice case studies, you will find good examples in the common case literature but also on PrepLounge. Although cases might follow some standard frameworks and applying those frameworks can help a lot, each case is an individual challenge. The best way to prepare is to read some cases, study the frameworks and the basics (e.g. P&L, revenue and costs), attend case question workshops and practice with friends, other students or consultants. Please be aware that you are not allowed to use a calculator.
In the interview, we want to judge how logically and persuasively you can present a case and we won't use the same case more than once. We do not publish any mock cases but we will offer you a briefing package, which will help you preparing for your recruiting day. And if you have any further questions regarding the interviews, please do not hesitate to contact an HR colleagues.