ΔE 18.7, loose: different enough that you should pick on purpose. Mana Regeneration is noticeably lighter, cooler than Celestium Blue.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 19). Mana Regeneration is noticeably lighter, cooler than Celestium Blue.
The same difference applies the other way round: Celestium Blue is noticeably darker, 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 Celestium Blue on the colour wheel See Mana Regeneration on the colour wheel
All matches: Celestium Blue equivalents · Mana Regeneration equivalents