ΔE 13.0, fair: the same colour family, but not a straight swap. Dark Reaper is cooler than Phthalo Green.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 13). Dark Reaper is cooler than Phthalo Green.
The same difference applies the other way round: Phthalo Green is 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 Phthalo Green on the colour wheel See Dark Reaper on the colour wheel
All matches: Phthalo Green equivalents · Dark Reaper equivalents