Second Interview is the hardest. There is a group activity, followed by a presentation in the morning. I feel that it was just a formality. The hardest is the panal interview in the afternoon. They will ask you technical questions and about projects undertaken. Know the technical aspect of your project very well. It is the hardest cause you are talking to Engineers with more than 10 years of experience. It highly depends on your interviewer as well, my interviewer asked alot of technical questions, whereas other interviewers only ask 1 technical question (heard from my friend who were interviewed in another room).