"Sleep Has His House" from the album of the same name. Written by vocalist David Tibet as an elegy to his father, the song itself comes at the tail end of a massive twenty-minute harmonium drone (interlaced with soft, mournful voices), and consists primarily of a long list of objects that, one realises, are meaningless in the face of death. It culminates with David Tibet nearly screaming, over and over, a variation on the lines spoken beneath the opening drone
Current 93 and Nick Cave's cover of "All the Pretty Little Horses". The original itself is already heartbreaking when you learn its origin: it was traditionally sung by African-American women who, as slaves, were often forced to care for their masters' children while neglecting their own (which is referenced in the second verse with a lamb "crying for her mammy").
"The Beautiful Dancing Dust", off Black Ships Ate the Sky. It's a beautiful, calming, almost lullaby-like piece so sweet and sincere that it might actually make you accept your forthcoming, immediate destruction.