Chords in B Locrian

B Locrian is built from the notes B, C, D, E, F, G and A. It uses no sharps or flats at all. Harmonising that scale in thirds gives seven chords — 3 majors, 3 minors and 1 diminished — starting on Bdim as the iø. The chord on the fifth degree is F, a major bV, so B Locrian has the leading tone that makes a F-to-Bdim cadence sound final.

Beyond those seven, B Locrian commonly borrows B (I), C#m (ii), D#m (iii), E (IV) and F# (V) from the parallel major — the mixture chords that give a progression somewhere unexpected to go.