ΔE 11.6, fair: the same colour family, but not a straight swap. Terror Blue-Grey is a little lighter than Obsidian Pigment Toner.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 12). Terror Blue-Grey is a little lighter than Obsidian Pigment Toner.
The same difference applies the other way round: Obsidian Pigment Toner is a little darker.
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 Obsidian Pigment Toner on the colour wheel See Terror Blue-Grey on the colour wheel
All matches: Obsidian Pigment Toner equivalents · Terror Blue-Grey equivalents