The Final Feast (2003)

From the file's introduction

A feast—is there any better or more universal way to memorialize an important affair? No matter what event is being commemorated, nothing brings people together like copious amounts of food, drink, and conversation.

The Final Feast takes place on Thanksgiving Day in a major U.S. city. A group of fanatical cultists uses an arcane ritual to transform homeless people partaking of a local food bank’s holiday feast into ravenous monsters with insatiable appetites.

A Short Urban Arcana Adventure for Four 11th-Level Characters