ΔE 10.4, fair: the same colour family, but not a straight swap. Magenta is a little lighter, cooler than Blood for the Blood God. They are different kinds of paint: Citadel Blood for the Blood God is a technical paint or medium and Scale75 Magenta is an opaque base/layer paint, so they won’t behave the same on the model even where the colour is close.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 10). Magenta is a little lighter, cooler than Blood for the Blood God. They are different kinds of paint.
The same difference applies the other way round: Blood for the Blood God 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 Blood for the Blood God on the colour wheel See Magenta on the colour wheel
All matches: Blood for the Blood God equivalents · Magenta equivalents