Sea of Clouds

Sea of Clouds is Disc 5, Track 11 on the Xenoblade2 Original Soundtrack. It plays in the following cutscenes of the main game of Xenoblade Chronicles 2:
 * Rex and Azurda see a Titan dying and sinking beneath the clouds.
 * Mythra speaks with Fan la Norne, wondering why she no longer calls herself 'Haze'.
 * Mythra and Poppi make promises for each other in the Land of Morytha.
 * A vision of Azurda asks Rex unanswerable questions in the First Low Orbit Station.
 * The Architect tells the party of the results of his goal of recreating life, and his inaction when Amalthus stole Logos and Pneuma and nearly destroyed the world.

It also plays in Xenoblade Chronicles 2: Torna ~ The Golden Country, when Azurda and Addam show the party the Tornan Titan's matrix.