This is the last mode of the harmonic minor scale, and because it has so many alterations (everything except the root is flatted) the use of this mode is somewhat limited, so the main chord this mode is used over is the diminished 7th.
|----------Octave------------||-----Extensions-------|
1-b2-b3-b4-b5-b6-bb7-8-b9-b10-b11-b12-b13
Chords generated by stacking 3rds from this mode:
1-b3-b5= Diminished Triad
1-b3-b5-bb7= Diminished 7th
1-b3-b5-bb7-b9= Diminished 7b9(Very Rare)
1-b3-b5-bb7-b9-b11= Diminished 7(b9b11)(Very Rare)
1-b3-b5-bb7-b9-b11-b13= Diminished 7(b9b11b13)(Very Rare)
What we are going to do now is rewrite some of the notes in here to their enharmonic equivalent, which will make it easier to see some of the other possible chord tones that can be built from this mode:
1-b2(b9)-b3(#9)-3-#4(#11)-#5-6-8
We can now see some of the dominant chords that can be made from this mode. Even though this mode does not have a minor 7th in it, we can still use this mode over chords which have this note in it, but also have an alteration in it as well.
Here are a few possible chords where this mode would work:
1-3-b5= Major Triad b5
1-3-#5= Augmented Triad
1-3-b5-b7= Dominant 7b5
1-3-#5-b7= Augmented 7
1-3-b5-b7-#9= Dominant 7(b5#9)
1-3-b5-b7-b9= Dominant 7(b5b9)
1-3-#5-b7-b9= Dominant 7(#5b9)
1-3-#5-b7-#9= Dominant 7(#5#9)
Example 1 is the obvious use of this mode, playing over a diminished 7th chord. Example 2 uses altered dominant chords. The first chord has the b5 already in it, while the second chord contains the #9(b2).
Vamp #1:(Ao7/Ebo7) (Use A Diminished. All black dots on A)
Vamp #2:(C7b5/C7#9) (Use C Diminished)
 |