Just got back from coaching Masters. This was definitely the favorite set of the week.
15 X 100, every 3rd 100 is up tempo. Use a sendoff that gives you approximately 25 seconds rest after your first 100.
After # 15, take an extra 60 to 90 seconds rest while you put on some fins. Then do a final 100 (#16) that is 25 swim/25 kick/25 swim/25 kick, and it should be FASTER than your fastest 100 from the first part of the set.