Gin, Campari, Amaro, Bitters, Orange bitters
Stir, strain into a coupe or over one large rock.
KC user BritInNoCal posted a similar variation, substituting Averna for the Negroni's sweet vermouth, on the KC Negroni page a day before Liu posted this blog update. Liu named his version for the Black Manhattan. Black Boulevardiers, Contessas, etc will probably work as well. A Black Nolita is probably excellent.