ΔE 21.7, loose: different enough that you should pick on purpose. Hexed Lichen is more muted, cooler than Witchbane Plum.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 22). Hexed Lichen is more muted, cooler than Witchbane Plum.
The same difference applies the other way round: Witchbane Plum is 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 Witchbane Plum on the colour wheel See Hexed Lichen on the colour wheel
All matches: Witchbane Plum equivalents · Hexed Lichen equivalents