This essay critically analyses the Situationist International's concept of a renewed model of avant-garde praxis, as developed in their 1963 exhibition called Destruktion-RSG-6, held at the Galerie Exi in Denmark. In a crucial, yet much overlooked, catalogue essay, 'Towards New Forms of Action in Politics and Art', Guy Debord presented a distillation of earlier Situationist writings on the avant-garde that, I argue, still generates productive conclusions. This includes a 'constructive' model of avant-garde practice that rejects the 'nihilistic' tendencies of 1920s Dadaism and Surrealism, as well as the 'spectacle of negation' associated with the so-called neo-avant-gardes of the 1960s, such as Happenings. It also provides a novel avant-garde temporality, one that takes place immanently, in the 'now' of time, but which involves a complex overlapping of past and present revolutionary moments. Debord calls this process the 'reversible connecting factor' whereby past, outmoded and forgotten avant-garde actions are salvaged through connections with current acts of cultural negation – but without recall to any lost originary avant-garde moment, contra Peter Bürger. In order to explain and develop the SI's model of immanent critique, and to show how their avant-garde theory takes practical form, I focus on the following exhibited works: Debord's series of painted 'Directives'; J.V. Martin's 'Thermonuclear Cartographs' and Michele Bernstein's 'Alternative Victory' series. These are analysed as practical instantiations of the concepts of 'positive negation', 'denial', 'black humour' and 'the false document', all of which play an important part in Debord's elaboration of the SI as the 'latest' avant-garde.