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What is the "potent black stone" in Black Gem Foundry dungeon?
Its used to get a buff or achievement you have to find a secret area and you find pieces to a staff around this room and you need a that potent soul gem to power it.
Xbox One - NA GT: RebornV3x
I also play on PC from time to time but I just wanna be left alone on there so sorry.
Like the others have said, but with these you get an bracelet/staff/whatever that you can buff 3 times after killing 3 different side bosses. There is a table in each room that you use the essence from the boss to build the bracelet. So you need 3 stones for the 3 bosses.