ΔE 7.4, close: similar, with a visible difference side by side. Ignis Fatuus is more saturated, cooler than Violet Coven.
Usually, if you are not matching paint already on the model. Close match (ΔE 7). Ignis Fatuus is more saturated, cooler than Violet Coven.
The same difference applies the other way round: Violet Coven is more muted, 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 Violet Coven on the colour wheel See Ignis Fatuus on the colour wheel
All matches: Violet Coven equivalents · Ignis Fatuus equivalents