Chords in Db Lydian

Db Lydian is built from the notes Db, Eb, F, G, Ab, Bb and C. Its scale carries 4 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 Ab, a major V, so Db Lydian has the leading tone that makes a Ab-to-Db cadence sound final.

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