ΔE 11.3, fair: the same colour family, but not a straight swap. Umbral Umber is more saturated than Abaddon Black.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 11). Umbral Umber is more saturated than Abaddon Black.
The same difference applies the other way round: Abaddon Black is more muted.
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 Abaddon Black on the colour wheel See Umbral Umber on the colour wheel
All matches: Abaddon Black equivalents · Umbral Umber equivalents