ΔE 11.9, fair: the same colour family, but not a straight swap. Warlock Magenta is a little darker, more muted than Amethyst.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 12). Warlock Magenta is a little darker, more muted than Amethyst.
The same difference applies the other way round: Amethyst is a little lighter, more saturated.
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 Amethyst on the colour wheel See Warlock Magenta on the colour wheel
All matches: Amethyst equivalents · Warlock Magenta equivalents