Calling it "absolutely appalling criminal behaviour", Judge Geoff Rea noted that although Allen believed the victim was dead as the pair fled in his car, the next morning she text-messaged a friend offering to sell the vehicle for a small amount of drugs - "LOL".
A person alleged to have been the second offender has denied being involved and is awaiting a trial.
Judge Rea said that while walking home a few days earlier, Allen met a man who was boarding with the eventual victim. They later traded messages and she visited the boarder at the house.
Her attempts to further contact the boarder, who had left the area, appeared to have been ignored and on June 24 Allen and a second person went to the house, knocked on the door and asked if the boarder was present.
They kicked the door as it was closed by the lone occupant after he told them no one else was there, and after drinking at a nearby address returned with the hammer which the second offender used to smash a glass pane at the entrance and gain access.
During the attack the man's phone and wallet were taken, and landline phone wires were cut.
The badly injured man shut himself in his bedroom for fear the attackers would return, and ultimately exited through a window and raised the alarm with a neighbour.
He was taken to hospital by ambulance and had multiple surgeries for his injuries, Judge Rea said.