ΔE 16.1, loose: different enough that you should pick on purpose. Skeleton Legion is noticeably darker, more saturated, warmer than Terminatus Stone.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 16). Skeleton Legion is noticeably darker, more saturated, warmer than Terminatus Stone.
The same difference applies the other way round: Terminatus Stone is noticeably 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 Terminatus Stone on the colour wheel See Skeleton Legion on the colour wheel
All matches: Terminatus Stone equivalents · Skeleton Legion equivalents