Harmonic minors use the relative major key signature and raise the seventh note of the scale. For example, in A harmonic minor there are no sharps or flats other than the raised seventh of G#.
Chords, scales ... bass (check out Examples 1 and 2 below). A polychord contains two complete triads played together. This isn’t always easy on the guitar, but the Em/maj9 (E minor and B major ...