The mysterious workshop on Blackstone Isle is locked tight. Inside are otherworldly creations, products of cruel machinations by the previous occupants. Now they lie idle and abandoned.

With this key you can put them to some use.

This grants access to the following items:

Arterial Engine
The bony blades of this grotesque engine are driven by a pulsing heart. It beats in time with your own.

Sign of Ruin
A symbol of the deep is carved into this small talisman. It's sure to draw the attention of those attuned to it.

More details on the official game page of DREDGE - Blackstone Key ...