piano scale
G♯ Phrygian
G♯1A♭2B♭3C♯4D♯5E♭6F♯♭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 A♭ 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
G♯HAWBWC♯WD♯HEWF♯WG♯
What is true of it
G♯ Phrygian is G♯, A, B, C♯, D♯, E and F♯, and back to G♯.
Its steps are H – W – W – W – H – W – W, where W is a whole step and H a half.
On the same tonic, G♯ natural minor differs from it by exactly one note.
Chords made only of these notes
C♯mminorC♯m7minor seventhD♯dimdiminishedD♯m7♭5half-diminished seventhEmajorEmaj7major seventhF♯mminorF♯m7minor seventh
Found by testing every chord in the catalogue against these 7 sounds, not chosen.