Chord sequence
B♯m7♭5 E♯7♭9 A♯maj7
In every key
Four-note rootless voicings in their two forms, with the 3rd or the 7th on the bottom, played over the root.
Heard in A# major
All the chords
A minor ii-V resolving to a major I: the half-diminished ii and the dominant's b9 darken the approach, then the major tonic brightens it.
Over B#m7b5 · iiø7
Mode 2 of Harmonic Minor
Over E#7b9 · V7♭9
Mode 5 of Harmonic Minor
Over A#maj7 · Imaj7
The major scale and its modes are the most commonly used scales in western music.