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 11th forms a tritone with the root and avoids the close clash that a perfect 11th creates with the 3rd. The combination of major 3rd, minor 7th, and #11 matches the Lydian dominant scale.
Application
Lydian harmony
Jazz and fusion
Film scoring
Voicing & structure
Root position
v1D#(D#4)Bass
root
v2G(G4)M3from D#
v3A#(A#4)m3from G
v4C#(C#5)m3from A#
v5E#(E#5)M3from C#
v6A(A5)M3from E#
Harmony
Compatible scales
All chord tones are contained in these scales — use them for improvisation.