Help me understand the theory behind this. The Final Countdown by Europe is everyone's favorite annoying intro riff. However it's got a pretty cool solo in the middle of it. The song is in the key of F#m so we've got F# - G# - A - B - C# - D - E notes to work with. During the solo, the following chords are being played behind it: F#m (F#-A-C) D (D-F#-A) Bm (B-D-F#) E (E-G#-B) The first solo is the part I have a question about. He's playing arpeggios over the chords above. As I understand it, the four arpeggios are: Bm arpeggio (B-D-F#) over the F#m C#dim arpeggio (C#-E-G) over the D major D arpeggio (D-F#-A) over the Bm G arpeggio (G-B-D) over the E major My first question is more of a general one related to playing an arpeggio over a chord. Are there any "rules" to go by? Example the Bm arpeggio over the F#m chord. All of the Bm notes are part of the F#m scale so I get that it would work but why a Bm arpeggio? Second is the C#dim and the G arpeggios. The G note in both arpeggios is not part of the F#m scale. Is simply changing to F# Phrygian here? How does the G major arpeggio not directly clash with the E major chord since it has a G# in it? Appreciate the help.