ΔE 13.6, fair: the same colour family, but not a straight swap. Firethorn Brown is a little darker, warmer than Astorath Red.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 14). Firethorn Brown is a little darker, warmer than Astorath Red.
The same difference applies the other way round: Astorath Red is a little lighter, cooler.
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 Astorath Red on the colour wheel See Firethorn Brown on the colour wheel
All matches: Astorath Red equivalents · Firethorn Brown equivalents