The Forge Key is a miscellaneous Story Item found in Act Three.

A small iron key.
Properties
Miscellaneous Items
Rarity: Story Item
Weight: 0.01 kg / 0.02 lb
Price: 1 gp
UID
UNI_LOW_Key_DiabolicForgeUUID
21727b7b-1ed0-40e8-a329-1daa1cec511a
Where to find
- Carried by the owner of Forge of the Nine