The Impending Crisis

The Impending Crisis is Disc 4, Track 4 on the Xenoblade2 Original Soundtrack. It plays in the following cutscenes of the main game of Xenoblade Chronicles 2:
 * Malos suddenly attacks Rex in Bana's room.
 * Lila flees and fights Ardainian soldiers on the rooftops of Alba Cavanich.
 * Jin, controlling Aeshma, begins his assault on the Urayan forces in Temperantia.
 * The party considers how to stop Aeshma's attack.
 * Bana causes Giga Rosa to explode after his defeat in Indol.
 * Genbu, out of Pandoria's control, begins diving into the Cloud Sea.
 * Malos calls forth Ophion in the Cliffs of Morytha, and reprograms it to follow his own will.
 * Rex and Nia land their cell-replicating attack on Malos in the Balqors Ruins.
 * The party finds themselves on a balcony of the World Tree, and observe the battle between Indol and the Marsanes.
 * Mor Ardain, under Amalthus's control, joins the fray at the World Tree.

It also plays in the following cutscenes in Xenoblade Chronicles 2: Torna ~ The Golden Country:
 * Lora and Jin finish off the attacking Volffs in the Lasaria Woodlands.
 * Malos's Gargoyle attacks Lora and Jin in Lasaria, but is destroyed by Mythra's Siren.