ΔE 12.1, fair: the same colour family, but not a straight swap. Viking Grey is noticeably lighter than Remove Mana.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 12). Viking Grey is noticeably lighter than Remove Mana.
The same difference applies the other way round: Remove Mana is noticeably darker.
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 Remove Mana on the colour wheel See Viking Grey on the colour wheel
All matches: Remove Mana equivalents · Viking Grey equivalents