ΔE 50.7, loose: different enough that you should pick on purpose. Umber Wash is noticeably lighter, much more muted, warmer than Drakenhof Nightshade.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 51). Umber Wash is noticeably lighter, much more muted, warmer than Drakenhof Nightshade.
The same difference applies the other way round: Drakenhof Nightshade is noticeably darker, much 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 Drakenhof Nightshade on the colour wheel See Umber Wash on the colour wheel
All matches: Drakenhof Nightshade equivalents · Umber Wash equivalents