ΔE 12.0, fair: the same colour family, but not a straight swap. Acid is a little lighter, more muted, cooler than Mantis Warriors Green. They are different kinds of paint: Citadel Mantis Warriors Green is a one-coat contrast-style paint and Vallejo Acid is a fluorescent or effect paint, so they won’t behave the same on the model even where the colour is close.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 12). Acid is a little lighter, more muted, cooler than Mantis Warriors Green. They are different kinds of paint.
The same difference applies the other way round: Mantis Warriors Green is a little darker, more saturated, 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 Mantis Warriors Green on the colour wheel See Acid on the colour wheel
All matches: Mantis Warriors Green equivalents · Acid equivalents