ΔE 22.9, loose: different enough that you should pick on purpose. Bag of Bones is a little lighter, more muted, warmer than Garaghak's Sewer.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 23). Bag of Bones is a little lighter, more muted, warmer than Garaghak's Sewer.
The same difference applies the other way round: Garaghak's Sewer is a little darker, 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 Garaghak's Sewer on the colour wheel See Bag of Bones on the colour wheel
All matches: Garaghak's Sewer equivalents · Bag of Bones equivalents