Synonyms of cataclysmic

2 Syllables
fatal, wreckful, ruinous, harmful, tragic
3 Syllables
tumbledown, hellfire, unlucky, disastrous
4 Syllables
lethiferous, cataclysmal, destructive, calamitous, catastrophal, catastrophic
5 Syllables
extirpative, fire-and-brimstone
6 Syllables
annihilative, eradicative