ΔE 12.5, fair: the same colour family, but not a straight swap. Deep Magenta is a little darker, more muted, cooler than Magnus the Red.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 13). Deep Magenta is a little darker, more muted, cooler than Magnus the Red.
The same difference applies the other way round: Magnus the Red is a little lighter, more saturated, 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 Magnus the Red on the colour wheel See Deep Magenta on the colour wheel
All matches: Magnus the Red equivalents · Deep Magenta equivalents