Here are some synonyms for "baleful":
* Threatening
* Menacing
* Sinister
* Ominous
* Harmful
* Malevolent
Examples:
* "The old house had a baleful aura, as if something terrible had happened there."
* "The general's baleful glare sent a shiver down the soldiers' spines."
* "The villain's baleful laughter echoed through the empty castle."
It's important to note that "baleful" often carries a connotation of evil intent, rather than simply being harmful by accident.