My case (as per wiki) for the presentation and interview was operational/IT, despite the role being in FS. The presentation only lasts 10min and after a few questions you're into the main interview.The written exercise includes all of the information you need, but it does state you can bring in external knowledge if relevant. The exercise was almost solely communication based and just required taking the relevant parts from the handout and summarizing them in a briefing document.As far as I'm aware Deloitte don't do 'case' style interviews, as you'd find at MBB and the like, so no need to worry about that, however those principles may help structuring your approach to presentations and written cases.By the way, this was for Senior Consultant/Manager. I don't know if then process changes for levels above.