From publisher blurb:
Libri Necromatica is a GSL gaming expansion for D&D 4E that brings necromancers into the campaign as both player characters and GM run monsters. The necromancer is presented as a half class, similar to the spell scar rules, allowing feat based multiclassing. There are also rules compliant with the newer mixed class approach detailed in the Player's Handbook 3.
Six paragon paths are presented. Danielle's Deckhand (an ocean going sort seeking lore about Davey Jones), the Blackguard (yes, that old prestige class is back), the Guardian of Mortality (the buffer between the spirits of the living and the dead), the Lich Apparent (they have plans for their deaths, big plans), the Shadowfell Dancer (a necromancer more interested in the Shadowfell than undead) and the Vampire's Lover (who will convince a vampire lord to make them one too - or die trying).
For the DM there are substitute powers to plug into other monster stat boxes to make them necromatic versions, templates for elite monster types, and four sample necromatically oriented monsters ready for use.
Spells are color coded as per the 4E Player's Handbook and organized in the same manner.