Hearts of Stone

From publisher blurb:

A 5th Edition Mini-Dungeon for four to six characters of level 7

To worship the Threshold Goddess is to seek hidden knowledge in secret places. That pursuit is never easy. For some, it is fatal.

Virna Dudavre was one such victim of the goddess’s caprice. Following the dreams and portents of her patron, the dwarven warlock lived a lonely life of toil, picking out a series of tunnels and chambers in an isolated, iron-poor hillside.

She sought to break through the barrier between worlds, chipping away at the layers of strata that separate realities. What she did not know was that her calling was a competition. There was another follower of the Threshold Goddess on the other side, and she was racing to break through first.