I did their AC last cycle. It is a partner case study plus a role play exercise with two senior associates. You have 5 minutes to read over a short brief about a business scenario and then the 2 partners will ask you questions based on that. After the case study, they ask you competency based questions like why commercial law, why Dentons, tell me about a time when you did X etc.
The role-play exercise was quite intense. You have 45 minutes to read over a pack about a business trying to expand. You have to write up a report to summarise the business and make some suggestions (so 45 minutes for both reading the materials and writing the report). There's a lot of details and you won't have time to read everything so make sure you skim and find the relevant bits. They will print your report out for you to bring in to present it to the two senior associates in a 'fake meeting' (hence it's a role-play). They are playing your senior colleagues. They will also ask you questions based on your suggestions. The key here is to stand your ground and give your reasons, even if they really challenge you. They do that on purpose to see if you back down without good reasons.
Good luck and hope this helps!
