To learn Cast - The Nightmare Before Christmas, Danny Elfman - (From The Nightmare Before Christmas/Soundtrack Version) Jacks Obsession chords, begin by getting comfortable with these sequence: Cm, Ab, G, Gb, B, C, B, Em, F, Bb and Gb. Adjust your pace with the tempo control on ChordU, starting slowly and speeding up progressively. For a balanced pitch, adjust the capo with respect to your voice and the song's key: Eb Major.