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

For further exploring for "nihilistic" in Webster Dictionary Online