(a.) Of, pertaining to, or characterized by, nihilism.

Cassandra-like Cassandran Cassandrian anarchial anarchic anarchistic anarcho-syndicalist antinomian baneful calamitous cataclysmal cataclysmic catastrophic chaotic consuming consumptive cynical deadly defeatist demolishing demolitionary depredatory desolating destroying destructive devastating disastrous dismal disorderly disorganized doomful downbeat extreme extremist extremistic fatal fateful fratricidal gloomy internecine mildly radical negative negativistic nihilist pessimist pessimistic pink radical ravaging red revolutionary revolutionist ruining ruinous self-destructive subversionary subversive suicidal syndicalist syndicalistic ultraconservative ultraist ultraistic uncheerful unruly vandalic vandalish vandalistic wasteful wasting withering