ΔE 11.7, fair: the same colour family, but not a straight swap. Necromancer Cloak is a little darker, more saturated than Russian Uniform.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 12). Necromancer Cloak is a little darker, more saturated than Russian Uniform.
The same difference applies the other way round: Russian Uniform is a little lighter, 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 Russian Uniform on the colour wheel See Necromancer Cloak on the colour wheel
All matches: Russian Uniform equivalents · Necromancer Cloak equivalents