ΔE 13.7, fair: the same colour family, but not a straight swap. Permanent Violet Dark is noticeably darker, more saturated, warmer than Warlock Magenta.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 14). Permanent Violet Dark is noticeably darker, more saturated, warmer than Warlock Magenta.
The same difference applies the other way round: Warlock Magenta is noticeably lighter, more muted, cooler.
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 Warlock Magenta on the colour wheel See Permanent Violet Dark on the colour wheel
All matches: Warlock Magenta equivalents · Permanent Violet Dark equivalents