ΔE 20.6, loose: different enough that you should pick on purpose. Warlock Magenta is noticeably darker, more muted, warmer than Blue Violet.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 21). Warlock Magenta is noticeably darker, more muted, warmer than Blue Violet.
The same difference applies the other way round: Blue Violet is noticeably lighter, more saturated, 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 Blue Violet on the colour wheel See Warlock Magenta on the colour wheel
All matches: Blue Violet equivalents · Warlock Magenta equivalents