ΔE 14.5, fair: the same colour family, but not a straight swap. Naggaroth Night is a little darker, warmer than Prussian Blue.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 15). Naggaroth Night is a little darker, warmer than Prussian Blue.
The same difference applies the other way round: Prussian Blue is a little lighter, cooler.
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 Prussian Blue on the colour wheel See Naggaroth Night on the colour wheel
All matches: Prussian Blue equivalents · Naggaroth Night equivalents