Cultist Purple vs Cygnar Blue Base

How close are they?

ΔE 18.0, loose: different enough that you should pick on purpose. Cygnar Blue Base is a little darker, more saturated, cooler than Cultist Purple.

Can I use Cygnar Blue Base instead of Cultist Purple?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 18). Cygnar Blue Base is a little darker, more saturated, cooler than Cultist Purple.

Can I use Cultist Purple instead of Cygnar Blue Base?

The same difference applies the other way round: Cultist Purple is a little lighter, more muted, 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.