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