Citadel Xereus Purple Layer Paint is designed to be multi-layered. This purple color is slightly transparent, so you can use it to build your color over several layers until you're happy with it. Now the paint does require a bit of practice to use, but the results are well worth it.
The layer paints are best used as a 2-step highlight, so two paints for each color but this is a guideline. For example, Xereus Purple can be combined with Genestealer Purple. You start with the darker of the two and apply it to the surfaces that you want to eventually provide this purple color.
Because the paint is a bit transparent you will continue to see the base color a bit, but by using Xereus Purple together with Genestealer Purple you can use that transparency to apply the layers. If you apply the lightest color after the darkest color in maybe 1 or two layers, the last highlight of the lightest color will ensure that you have a great result.
The color of Citadel Xereus Purple (22-09) is similar to: The Army Painter Alien Purple (WP1128); Old Citadel Liche Purple; Vallejo Game Color Hexed Lichen (72015); Vallejo Model Color Royal Purple (70810); Rackham Divine Purple (6); Reaper Master Clear Plum (9132); Privateer Press P3 Beaten Purple; Coat D'arms Poison Purple (118).