Beyond the Veil (2001)

from the back of the book

Stories about dragons rampaging across the countryside are almost always false.

The creatures are just too intelligent, too crafty, and too strategy-minded to "rampage." Rampaging brings the wrath of oath-bound knights, powerful mages, and divinely-protected priests. Why would a dragon want such attention, unless it had some special secret, or unless it was insane?

Or both.

The northern reaches of the Derideth Swamp were once plagued by a rampaging dragon. This black dragon, named Storamere, took a mad glee in attacking human villages, wiping out orc camps, driving off the lizardfolk, and decimating farmland. He met his untimely end, though, in an ambush devised by the monks of the Order of St. Chausle. Storamere died with a curse upon his draconic tongue: "you could not have defeated me in my lair," he told his slayers. "I am forever invincible in my lair."

Now Storamere is back, with a horde of his misshapen half-dragon offspring, to have his vengeance. All that remains of the once-heroic monks are two old men driven mad by their last encounter with the black dragon, so it falls to a band of adventurers to again defeat the mighty dragon -- this time in his palace, where the boastful Storamere claims he is at his strongest.

Beyond the Veil is an OGL adventure designed for characters of 9th level and up. It includes:

Stats for the deviant Storamere's half-dragon progeny, including a monstrous stone giant, umber hulk, giant constrictor, manticore, carrion crawlers, and dark elves, all with dragon parentage.
New OGL rules for dragon bloodspawn -- those creatures with a quarter dragon blood in their heritage -- and stats for a bloodspawn vampire.
Maps and damage rules for navigating Storamere's lair, a semi-solid palace made of a dangerous, corrosive liquid five feet thick and located in another plane.