ΔE 45.3, loose: different enough that you should pick on purpose. Deep Metallic Blue is a little lighter, much more saturated than Night Scales.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 45). Deep Metallic Blue is a little lighter, much more saturated than Night Scales.
The same difference applies the other way round: Night Scales is a little darker, much more muted.
ΔE is the colour difference between our two swatch estimates: under about 6 is close, over about 15 is loose. Real paints also differ in finish, coverage and how they thin, so test before you commit.
See Night Scales on the colour wheel See Deep Metallic Blue on the colour wheel
All matches: Night Scales equivalents · Deep Metallic Blue equivalents