Sly Flourish's Fantastic Adventures: Ruins of the Grendleroot - The Call of Starsong Tower (2020)

From publisher blurb:

For a thousand thousand years, an ancient entity has been trapped in the heart of a mountain formed from rock not of this world. Over eons, creatures both monstrous and intelligent have explored the endless tunnels, caverns, and chambers of Blackclaw, answering the call of the mysterious entity buried within it. Over long centuries, hundreds of lairs, cities, keeps, prisons, and tombs were established within the mountain, but even those centuries of exploration did not uncover all its secrets.

Then, two centuries ago, the entity now known as the Grendleroot awoke.

Indestructible black spires shot through the rock of the mountain like the roots of a deadly weed, shattering civilizations, burying cities, and exposing caverns long lost. Today, adventurers residing in Deepdelver’s Enclave explore these lost ruins once again. They seek fellow adventurers brave enough to answer the call of Blackclaw, and to seek the mysteries of the Grendleroot.

Call of Starsong Tower is a free 1st level adventure for the 5th edition of the world's most popular roleplaying game. This is the first of ten adventures available in Fantastic Adventures: Ruins of the Grendleroot.