Possible Clues:

• Second section of Verdi's "Requiem"
• Requiem Mass hymn
• Part of a Requiem Mass
• Part of a requiem Mass
• Judgment Day hymn
• Medieval Latin hymn about Judgment Day
• Passes on fury about Academy's Latin hymn
• Well-known hymn
• Hymn featuring in a Requiem Mass
• Latin hymn (day of wrath)