Darkoath Flesh vs Drain Life

How close are they?

ΔE 21.0, loose: different enough that you should pick on purpose. Drain Life is noticeably lighter, more saturated than Darkoath Flesh.

Can I use Drain Life instead of Darkoath Flesh?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 21). Drain Life is noticeably lighter, more saturated than Darkoath Flesh.

Can I use Darkoath Flesh instead of Drain Life?

The same difference applies the other way round: Darkoath Flesh is noticeably darker, more muted.

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.