Synonyms for Baleful (same or very similar meaning)
WordNet sense 1 (deadly or sinister):
banefulWordNet sense 2 (harmful or evil in intent or effect):
maleficent, maleficentWordNet sense 3 (threatening or foreshadowing evil or tragic developments):
forbidding, menacing, minacious, minatory, ominous, sinister, threateningWordNet sense 4 (causing alarm or fear):
alarmingFrom the ODE community, based on WordNetadd/edit