This photo here is the first run I had done in Tidemistress Athissa from the Warcraft expansion, Legion. She was made for Dragoncon 2016, for the video game costume contest, and ended up winning best in show with her! The costume took about two-three months to work on, and is comprised mostly of l200 foam and resin. There are some spots that need adjustment (such as how the tail that follows connects to the skirt portion, and how the bra piece connects to the shoulderpieces, as well as the weight of the headpiece) but I found it to be a very fun, and awesome challenge.
All of the gems light up, though it is hard to tell with the pic, as it was taken during the daytime. The tail that follows me ended up being about 9-10 in length. It was a very difficult costume to move around in, and stairs were impossible.