D# dim/D
The D# dim chord consists of the D# (Perfect unison), F# (Minor third) and A (Diminished fifth) notes, with D as the bass note.

How to play the D# dim/D chord
- Play D as the lowest bass note in the left hand
- Find D# (Root) on the piano keyboard
- Add F# (Minor third) — 3 semitones above D#
- Add A (Diminished fifth) — 6 semitones above D#
- Press all 4 notes simultaneously to sound the D# dim/D chord