Asurmen Blue vs Mana Regeneration

How close are they?

ΔE 18.6, loose: different enough that you should pick on purpose. Mana Regeneration is noticeably lighter, more saturated, cooler than Asurmen Blue.

Can I use Mana Regeneration instead of Asurmen Blue?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 19). Mana Regeneration is noticeably lighter, more saturated, cooler than Asurmen Blue.

Can I use Asurmen Blue instead of Mana Regeneration?

The same difference applies the other way round: Asurmen Blue is noticeably darker, 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.