ΔE 12.0, fair: the same colour family, but not a straight swap. Runic Purple is noticeably darker than Lucius Lilac.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 12). Runic Purple is noticeably darker than Lucius Lilac.
The same difference applies the other way round: Lucius Lilac is noticeably lighter.
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 Lucius Lilac on the colour wheel See Runic Purple on the colour wheel
All matches: Lucius Lilac equivalents · Runic Purple equivalents