From the publisher:
In unquenchable hunger, there is un-deflatable strength. Grendel Spawn are the world's ultimate predator, a cunning and bloodthirsty omnivore designed to bring down the most dangerous (and most delicious) prey: homo sapiens.
Grendel Spawn are deadly aberrations that seem to draw on the primal nature of hunger itself. Their chainsaw-like maws can shred bone and tissue, and they posses an entire host of deadly gifts. As the Grendel Spawn ages, a pinpoint singularity opens in her belly: soon nothing can escape her mouth. Steel and magic alike fall to the Grendel Spawn, and when she hungers, not even light can escape her.
Included in this Advanced Class are a host of new abilities, eight new feats and all the information required to introduce these deadly predators into your D20 Modern game!