ΔE 31.4, loose: different enough that you should pick on purpose. Necrosis Green Wash is much more muted, cooler than Seraphim Sepia.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 31). Necrosis Green Wash is much more muted, cooler than Seraphim Sepia.
The same difference applies the other way round: Seraphim Sepia is much 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 Seraphim Sepia on the colour wheel See Necrosis Green Wash on the colour wheel
All matches: Seraphim Sepia equivalents · Necrosis Green Wash equivalents