Tritone substitution: D#7 can be replaced by A7 (a tritone away). Both chords share the same tritone between the 3rd and 7th, resolving to the same tonic.
The augmented 9th is enharmonically equivalent to a minor 3rd and sounds alongside the chord’s major 3rd. Their chromatic clash creates sharp tension characteristic of blues and rock.
Application
Blues rock (Jimi Hendrix "Purple Haze")
Funk
Jazz fusion
Voicing & structure
Root position
v1D#(D#4)Bass
root
v2G(G4)M3from D#
v3A#(A#4)m3from G
v4C#(C#5)m3from A#
v5F#(F#5)P4from C#
Harmony
Compatible scales
All chord tones are contained in these scales — use them for improvisation.