Super-Locrian bb7 (altered diminished)
The altered scale with its 7th lowered once more — the seventh mode of harmonic minor, as dark as scales get.
A, crotchet; B flat, crotchet; C, crotchet; D flat, crotchet; E flat, crotchet; F, crotchet; G flat, crotchet; A, crotchet
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A B♭ C D♭ E♭ F G♭