She was piqued at being ignored by a former boarder of the victim.
But it was a person who was with her who is said to have bashed the victim with a hammer the pair took to the scene.
A piece of firewood from the man's lounge was also used as a weapon, leaving him unconscious with multiple facial fractures, and fingers broken from trying to protect himself against the blows with the weapons, the punches and the kicking.
The victim's car was also stolen.
Carroll was arrested last July and charged with the same counts as Allen but pleaded not guilty to both charges in the Hastings District Court.
Her trial started on Monday with a jury being chosen and witnesses being called including the victim and Allen. Some written witness statements were also read.
Allen's cross-examination continued yesterday morning with questions from crown prosecutor Jo Rielly and defence counsel Matt Phelps.
Allen said she would not tell the court who else was involved in the attack but rather who was not; this included her brother and an acquaintance.
Other witnesses took to the stand yesterday including Constable Ryan Palmer, the officer called to the victim's neighbour's address shortly after the incident.
He told the court the victim had blood pouring from his head.
The victim told him two women had broken into his home and attacked him with a hammer.
They had come to his address earlier in the evening looking for his flatmate (who had recently moved out), Constable Palmer said.
Forensic scientist Glenys Knight explained in detail different aspects of forensic evidence found at the victim's address, including blood, and also spoke about methods used to analyse evidence.
The trial continues at 10am today and is expected to finish tomorrow.