Ok, in that case you are likely to have similar format as me.
You have an hour to prepare a presentation from a case study. I suggest you review the case studies on their site, get a feel for flow and structure. You can't really prepare for the content, so think about the value prop of the area you are going for and rry to embed that in your presentation.
Next you have partner level interview. (60 mins allowed)Mine was very straightforward, I ended up asking him more questions that he did. Again not a lot you can prepare for expect for your motivations to work for Deloitte, 3-5 year career plan, etc.
Then you have up to 45 mins for the actual presentation. Timing is important. I used a stop-watch. You have 10 mins to present, if you exceed by a couple of mins then that's fine. This will be followed-up by questions from the panel. On the spot questions, so your experience and subject matter knowledge will be tested.
Finally, the group exercise. It was only me on that day, so I skipped this. Your level of participation is observed. Don't necessarily try to take the lead or take the back-seat, influencing at the right level. Throw in thought-provoking questions.
There are some threads on here which I found useful prior to my session. Don't over-prepare yourself. I didn't think it was that bad. Just be confident and go with the flow!