piano scale
D♯ whole tone
D♯1E♯2F𝄪3G𝄪♯4A𝄪♯5B𝄪♯6
Six notes, every step a whole one. There are only two of these scales in all, and every note can be heard as the tonic.
The same sounds spelled from the other side are E♭ whole tone.
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
D♯WE♯WF𝄪WG𝄪WA𝄪WB𝄪WD♯
What is true of it
D♯ whole tone is D♯, E♯, F𝄪, G𝄪, A𝄪 and B𝄪, and back to D♯.
Its steps are W – W – W – W – W – W, where W is a whole step and H a half.
Written correctly it needs 10 alterations, F𝄪, G𝄪, A𝄪 and B𝄪 among them. That is what the letters force, and it is also why nobody writes music in this key: the same notes spelled from the other side are easier to read.
Chords made only of these notes
Found by testing every chord in the catalogue against these 6 sounds, not chosen.