Formula: Nigredo

Formula: Nigredo is an alchemy formula in that is needed to craft nigredo.
It is guaranteed to appear in the locked safe during the secondary quest Novigrad, Closed City, but it can also be found at a random diagram location or purchased from the following merchants:
* The Pellar near Blackbough
* Gremist at Gedyneith
* Merchant in the Perfumery in Beauclair 
* Wine Merchant at Chuchote Cave 
* Wine Merchant at Dun Tynne Hillside 
pl:Receptura: Nigredo
ru:Рецепт: Нигредо
Category:The Witcher 3 alchemy formulae