Sources have confirmed to Newshub former press secretary Rachel MacGregor is suing her former boss Colin Craig.
She filed papers in Auckland's High Court on Tuesday, counter-suing Mr Craig.
It comes after it was revealed Mr Craig had filed defamation action against Ms MacGregor, which have not yet been served.
The papers filed by Ms MacGregor have been served on Mr Craig, sources confirmed to Newshub.
Ms MacGregor and Mr Craig had a public falling out after she quit her job two days before the 2014 election.
They signed a confidentiality agreement as part of the settlement of a sexual harassment and pay claim, but Mr Craig went on to repeatedly break it.
Ms MacGregor took a case to the Human Rights Tribunal, which ordered Mr Craig to pay her more than $120,000.
Mr Craig's latest lawsuit comes two months after he sued a former employee for $240,000. And in February, a defamation claim by Mr Craig against Mr Stringer was settled out of court.
Mr Craig has also sued Mr Slater for copyright infringement, after the blogger posted the failed politician's poetry on his blog. Mr Craig lost that case, the judge calling his lawsuit "vexatious" and a "waste of the court's time". Mr Craig has appealed.