The Locrian mode is the darkest and most ominous mode derived from the parent scale, the major scale (the Ionian mode). The reason is due to it having the Phrygian mode's minor 2nd, 3rd, 6th and 7th PLUS the 5th is diminished. Making the 5th a diminished 5th makes the scale and associated chords very tense. For the full tutorial's video, tab, audio and advice tips visit