Composer is Hiroyuki Sawano, best known for his great work on Sengoku Basara (anime) and Gundam Unicorn :
http://www.youtube.com/watch?v=V6uScXSUggE
http://www.youtube.com/watch?v=ghlQswk82C0
http://www.youtube.com/watch?v=V6uScXSUggE
http://www.youtube.com/watch?v=ghlQswk82C0