Hellgate keep - a name that once made the boldest of heroes shudder in fear - was long ago known as the fair citadel of Ascalhorn, a haven for elves and humans. The the demonic horde of bateezu and tanar`ri destroyd all remnants of real cicilization and turnet it into a den of malevolence. Today, the citadel lies ruined. The mistmaster and the harpers destroyed the keep and ended its centuries-long reign of evil...or so they believed
"Far be it from me to impugn the mettle of adventurers such as yourselves, but daring the depths of Undermountain merely for fortune's sake is more absurd than kicking a sleeping dragon in the nose for sport. Even so, you've returned for another trip to the Underhalls, so be prepared. You stand to enter the Lost Level this time: Gird yourselves for diplomacy as well as destruction. You'll find the last stronghold of an extinct dwarven clan: Do be good enough to extend the greetings of the Blackstaff to Bandaerl. There's also a dark vampiress who enjoys a good hunt, and be sure to mind the beholders: They're trained to keep you from escaping. "Enjoy, and don't say Khelben didn't warn thee." TSR 9519