ΔE 19.2, loose: different enough that you should pick on purpose. Toxic Yellow is a little lighter, warmer than Mystic Green.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 19). Toxic Yellow is a little lighter, warmer than Mystic Green.
The same difference applies the other way round: Mystic Green is a little darker, 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 Mystic Green on the colour wheel See Toxic Yellow on the colour wheel
All matches: Mystic Green equivalents · Toxic Yellow equivalents