The first round was a timed video interview with a number of questions. The video was one-way with automated questions that you can read and have a certain amount of time to answer.

15min hirevue with pretty base level questions, know why you want to work at Mercer. After that, 1.5 hr interview with four consultants (2 per 45 min). Lots of questions based on your past experiences, why Mercer, etc.