ΔE 18.8, loose: different enough that you should pick on purpose. Glistening Gums is a little darker, more saturated, warmer than Warpfiend Grey.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 19). Glistening Gums is a little darker, more saturated, warmer than Warpfiend Grey.
The same difference applies the other way round: Warpfiend Grey is a little 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 Warpfiend Grey on the colour wheel See Glistening Gums on the colour wheel
All matches: Warpfiend Grey equivalents · Glistening Gums equivalents