Halaster's Maze of Madness

Publisher's blurb:

A 5E Adventure For Characters of Level 5 to 7

When the Mad Mage of Undermountain received visions of an apocalyptic event striking Waterdeep, he used a large runestone to build defenses against the catastrophe. But when he died during the process, his soul fractured and spread to the four corners of Faerun. Many share Halaster's visions now, and you are called upon to unravel the mysteries of the Maze Level of Undermountain and figure out what new peril awaits. Halaster's Maze of Madness includes an adventure, two new magic items, and nine new monsters.