piano scale
B Phrygian
B1C♭2D♭3E4F♯5G♭6A♭7
Minor with a flattened second — the half step right above the tonic is the whole character.
Written out
Every accidental is written in, rather than left to a key signature, so the letters can be read one at a time.
The step pattern
BHCWDWEWF♯HGWAWB
What is true of it
B Phrygian is B, C, D, E, F♯, G and A, and back to B.
Its steps are H – W – W – W – H – W – W, where W is a whole step and H a half.
On the same tonic, B natural minor differs from it by exactly one note.
Chords made only of these notes
CmajorCmaj7major seventhDmajorD7dominant seventhEmminorEm7minor seventhF♯dimdiminishedF♯m7♭5half-diminished seventh
Found by testing every chord in the catalogue against these 7 sounds, not chosen.