ΔE 14.2, fair: the same colour family, but not a straight swap. Royal Cloak is much more muted, cooler than Grimoire Purple.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 14). Royal Cloak is much more muted, cooler than Grimoire Purple.
The same difference applies the other way round: Grimoire Purple 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 Grimoire Purple on the colour wheel See Royal Cloak on the colour wheel
All matches: Grimoire Purple equivalents · Royal Cloak equivalents