ΔE 18.5, loose: different enough that you should pick on purpose. Purple is noticeably lighter, more saturated, cooler than Naggaroth Night.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 18). Purple is noticeably lighter, more saturated, cooler than Naggaroth Night.
The same difference applies the other way round: Naggaroth Night is noticeably darker, more muted, warmer.
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 Naggaroth Night on the colour wheel See Purple on the colour wheel
All matches: Naggaroth Night equivalents · Purple equivalents