ΔE 13.5, fair: the same colour family, but not a straight swap. Light Green RLM25 is noticeably lighter, more muted than Ruinous Spell.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 14). Light Green RLM25 is noticeably lighter, more muted than Ruinous Spell.
The same difference applies the other way round: Ruinous Spell is noticeably darker, more saturated.
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 Ruinous Spell on the colour wheel See Light Green RLM25 on the colour wheel
All matches: Ruinous Spell equivalents · Light Green RLM25 equivalents