They were relative no-bodies, really. Adventurers in their own right, most certainly, but still young and inexperienced in the grand scheme of things. They would find their legends merging at Waterdeep. In response to the aftermath of the magical cataclysm that was the SpellPlague, the Undermountain of the notorious Mad Mage Halaster has gone berserk.
Gone are the original denizens of this madhouse, replaced instead with the profane, the nauseating, and the outright bizarre. Traps once thought understood have mutated into something completely other, and even the layout of Undermountain itself appears to have been under reform. Even picking up an item is now a dangerous venture – identification magics have no effect in this new Undermountain, and most items carry a maddening mix of blessing and curse effects.
Beyond the knowledge of our party, a familiar laugh, once long-forgotten, echos through Undermountain halls. Apart from his puppetry, the Divine themselves have taken a personal interest in the matter, which could see one of their order redeemed and one finally brought to justice. Before it all plays out, a Succubus Paladin and Elminster himself will offer aid (though that may be less unusual than one thinks) and famed Waterdeep itself has a hand to play in the matter, to avoid Undermountain’s freakish new creatures from flooding the city itself!
Undermountain is a mad laboratory once more, and frankly, no one believes this ragtag ensemble will last even a day in such a hell. But it is by doing the impossible that legends are forged.