ΔE 11.5, fair: the same colour family, but not a straight swap. Arachnid Green is more saturated, cooler than Militia Green.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 12). Arachnid Green is more saturated, cooler than Militia Green.
The same difference applies the other way round: Militia Green is 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 Militia Green on the colour wheel See Arachnid Green on the colour wheel
All matches: Militia Green equivalents · Arachnid Green equivalents