Seeing her was an omen for storms, volcano eruptions and shipwrecks.
When she was full grown she killed many people with her powerful three heads which were able to attack independently of each other.
She was able to resist many attempts on her life until she met her fate - a poisoned spear thrown by Bellerophon. Of course he was riding
Pegasus
at the time which, I am sure had plenty to do with the final outcome of this deadly quarrel.