ΔE 10.0, fair: the same colour family, but not a straight swap. Silver Grey is a little lighter, cooler than Necromancer Cloak.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 10). Silver Grey is a little lighter, cooler than Necromancer Cloak.
The same difference applies the other way round: Necromancer Cloak 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 Necromancer Cloak on the colour wheel See Silver Grey on the colour wheel
All matches: Necromancer Cloak equivalents · Silver Grey equivalents