Rage, Darkness of the Heart

Rage, Darkness of the Heart (originally unofficially referred to as Anger, Darkness of the Heart) is Disc 2, Track 11 on the Xenoblade Original Soundtrack, and Disc 1, Track 18 on the Xenoblade Definitive Edition Original Soundtrack and the Xenoblade Chronicles Original Soundtrack Trinity Box.

It plays during these cutscenes:

Xenoblade Chronicles

 * The entrance to the Weapon Development Lab is blocked off by debris during the Mechon assault on
 * Metal Face leaves Colony 9 after the second battle
 * Otharon telling the party what happened to him and Gadolt in the Ether Mine
 * Xord's destruction after the second battle on the in the Ether Mine
 * Before the battle against Gold Face and in the Fortress Depths of Galahad Fortress
 * Meyneth proposing to break Gadolt's curse after his first battle at the Shrine Transporter in Agniratha
 * Egil moves to the Mechonis Core after the battle at the Meyneth Shrine in Agniratha
 * Shulk telling Egil that he won't kill him after the battle in the Mechonis Core
 * Lorithia turning Kallian and the other High Entia into Telethia after the battle against the on the Junks Deck
 * Dickson's death on the on Prison Island

Future Connected

 * When Gael'gar blows up Teelan's Laboratory