Chords in Db Mixolydian

Db Mixolydian is built from the notes Db, Eb, F, Gb, Ab, Bb and Cb. Its scale carries 6 flats. Harmonising that scale in thirds gives seven chords — 3 majors, 3 minors and 1 diminished — starting on Db as the I. The chord on the fifth degree is Abm rather than a major V, so Db Mixolydian has no leading tone and resolves by step and colour instead of by dominant pull — the sound that separates it from a plain Db minor.

Beyond those seven, Db Mixolydian commonly borrows Dbm (i), Ebdim (iiø), Fb (bIII), Gbm (iv) and Bbb (bVI) from the parallel minor — the mixture chords that give a progression somewhere unexpected to go.