piano scale
F♯ Phrygian
F♯1G♭2A♭3B4C♯5D♭6E♭7
Minor with a flattened second — the half step right above the tonic is the whole character.
The same sounds spelled from the other side are G♭ Phrygian.
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
F♯HGWAWBWC♯HDWEWF♯
What is true of it
F♯ Phrygian is F♯, G, A, B, C♯, D and E, and back to F♯.
Its steps are H – W – W – W – H – W – W, where W is a whole step and H a half.
On the same tonic, F♯ natural minor differs from it by exactly one note.
Chords made only of these notes
C♯dimdiminishedC♯m7♭5half-diminished seventhDmajorDmaj7major seventhEmminorEm7minor seventhF♯mminorF♯m7minor seventh
Found by testing every chord in the catalogue against these 7 sounds, not chosen.