進撃st20130629巨人 (S4E9) (Attack on Titan: The Final Season)
This was requested by Baggy juice and KapTooMuch_!
The OST is titled 進撃st20130629巨人 (also known as Shingeki st20130629 Kyojin). Hiroyuki Sawano is behind this masterpiece. The OST was slightly edited for episode 9. In the closing moments of the episode, a famous mirror scene with Eren was shown with this OST still playing