From publisher blurb:
Colours of Magic: Purple Fifth Edition Update
A Spectrum Shift: Chromatic Arcana Product
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.
Orange is the colour of Chaos, Disorder and Change.
Purple is the colour that flesh becomes when exposed to cold. It is the colour of death, unlife and the chill that is left at the end of all things. When all the other energies are spent and nothing else remains, all that is left is the frozen void. Those that seek to use magic to tap into this ultimate end often see the after effect of the Colour surrounding the aspects of their magic as all matter fades before the power of nothing. It is at the end of the spectrum, before everything fades into the Ultraviolet. Those with mastery over Purple magic are powerful necromancers and users of void magic. They can also drain the energy out of people and things, occasionally using it to extend their own powers.
Included in this product:
3 new Class options, one for each of Cleric (Mortician), Sorcerer (Vital Syphon) and Wizard (Voidspeaker)
a reclassification of one eleventh of the spells of the players handbook