ΔE 12.4, fair: the same colour family, but not a straight swap. Leviathan Blue is a little darker than Stormfiend.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 12). Leviathan Blue is a little darker than Stormfiend.
The same difference applies the other way round: Stormfiend is a little lighter.
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 Stormfiend on the colour wheel See Leviathan Blue on the colour wheel
All matches: Stormfiend equivalents · Leviathan Blue equivalents