From publisher blurb:
Gruesome undead templates are quick, easy options a GM can add to nearly any undead monster, to create creatures with whole new themes and abilities. A GM can use these as threats that are less familiar to experienced players, clues or elements for a specific background story, or to just have new boss undead to be the focus of a climactic final battle.
All the gruesome templates are designed to play into a specific fearsome idea or fate and provide an extra dose of horror for undead foes. Some of the gruesome templates are inspired by the ghosts, vampires, and zombies of classic horror fiction, while others are intended to tie into specific background or environmental themes. Each template includes all the game rules needed to run it (including a new mechanic, shock value, explained in detail below) and enough descriptive material and suggestions for use to make it easy for a GM to add them to an ongoing adventure or build whole new encounters around them.