ΔE 23.6, loose: different enough that you should pick on purpose. Crimson Hell is a little lighter, much more muted, cooler than Doombull Brown.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 24). Crimson Hell is a little lighter, much more muted, cooler than Doombull Brown.
The same difference applies the other way round: Doombull Brown is a little darker, much more saturated, warmer.
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 Doombull Brown on the colour wheel See Crimson Hell on the colour wheel
All matches: Doombull Brown equivalents · Crimson Hell equivalents