Kingdom hearts birth by sleep ost
Which is again remixed into "The Key", Aqua's (and Mickey's) final boss theme against Vanitas-possessed Ventus and his completed χ-Blade.
![kingdom hearts birth by sleep ost kingdom hearts birth by sleep ost](https://i1.sndcdn.com/artworks-000089543415-x09ujn-t500x500.jpg)
![kingdom hearts birth by sleep ost kingdom hearts birth by sleep ost](https://vgmsite.com/soundtracks/kingdom-hearts-birth-by-sleep-358-2-days-original-soundtrack/02.jpg)
There's some Fridge Brilliance with "Forze dell'Oscurita", as well: not only does it contain part of Xemnas' final battle music, but the section it borrows comes from when you're fighting Armored Xemnas, whose appearance is almost identical to No Heart's. It epically combines "Forze del Male" with "Darkness of the Unknown" for music of sheer power.
![kingdom hearts birth by sleep ost kingdom hearts birth by sleep ost](https://i.ytimg.com/vi/iHp1zi8nPns/hqdefault.jpg)
And it's even more awesome when you realize this is a song of Radiant Garden a.k.a.
![kingdom hearts birth by sleep ost kingdom hearts birth by sleep ost](https://theredepic.com/wp-content/uploads/2020/07/top-10-kh-ost-songs-min.png)