ΔE 20.6, loose: different enough that you should pick on purpose. Spirit Blue is a little lighter, much more saturated, warmer than Stormfang.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 21). Spirit Blue is a little lighter, much more saturated, warmer than Stormfang.
The same difference applies the other way round: Stormfang is a little darker, much more muted, 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 Stormfang on the colour wheel See Spirit Blue on the colour wheel
All matches: Stormfang equivalents · Spirit Blue equivalents