She killed her brother Apsyrtus and cut his body to pieces, while in pursuit on boats, everytime the Colchians got close she would throw a piece of his body out that they needed to retrieve
What was Medea's plan in order to get Jason on the throne?
She tricked the daughters of Pelias and showed them a magical ritual that would reverse his ageing process - the girls slaughtered their own father accidently.