Self-styled sharemarket enforcer Alan Davison has succeeded in a court application to amend his defence to a defamation claim launched against him by mining and stockmarket entrepreneur Tolga Kumova.

Justice Michael Lee’s decision sets the scene for a bitter courtroom battle that will take both from a Twitter spat to the witness box of the NSW Federal Court over allegations Mr Kumova engaged in insider trading, misled the market, and provided inside information about ASX-listed New Century Resources’ planned acquisition of the Goro Nickel Mine.