From the publisher:
In some worlds, Magic may not be seen as a force in and of itself. In some philosophies, magic can not be classed by types of effect, like Evocation, Illusion or Abjuration. Instead, it might be seen as a result of fundamental aspects of arcane metaphysics.
One such theory holds that all magic is a result of the principles of Colour.
Grey is the colour of the Shades, Illusions and Sound. Arcanists studying this style of magic can fool even the most astute of observers, making things appear, sound and even feel different to they actually are. The ultimate expression is destructive resonance so powerful it can kill with a sound, deceive even an Oracle, summon the powers of other colours from the realm of Shadows.
The most gifted of Grey specialists are Chymurges: Mages of the darker hues. Their skills are sometimes called cartomancy, but encapsulate far more than simple card tricks. They can manifest almost any style of magic, and then if needed, can fabricate and even enhance shadowy half-real versions of the other colours.
Included in this product:
3 new Clerical or Mystical domains
a linked reclassification of one twelfth of the spells of the players handbook, with some new spell effects to fit the spells into Chromatic Magic Theory
a whole new character class, the Chymurge. This spellcaster is gifted with cartomancy, and a great command over Grey magic.