Ravenloft: Van Richten's Guide to the Ancient Dead

From the Back of the Book:

In the caverns, crypts, and chasms of Ravenloft lie mummies and other horrors for whom sleep is a natural state. These are the ancient dead. Dreams of love, glory, and wealth subdue them through the ages, and time grows meaningless - until the greedy or foolish disturb their rest. When the ancient dead rise and walk again, evil spreads before them and destruction lies in their wake.