"He was punched and kicked a large number of times to the head and body."
Judge Davidson said Wallace was pulled away but managed to break free and continued to assault the victim.
Wallace had also been caught with 51 grams of cannabis when returning to the prison after being granted compassionate bail to attend his grandmother's tangi. He was initially charged with possession for supply but it was later reduced to possession.
Judge Davidson said Wallace, who has "mobster" tattooed across his face, had a dreadful criminal history spanning more than 20 years.
"It's amongst the worst that I've ever seen for some time."
He told the 38-year-old that as he approached 40, it was time to do some serious soul-searching and move away from his criminal behaviour.
Wallace, a father of five, was quick to accept the challenge telling the judge "I'm very sorry for everything".
"This place just seems to keep pulling me back in," he said.
"I am trying hard to stay out of trouble but I'm surrounded by rapists and murderers, a whole lot of criminals. I am trying, I am trying not to get into trouble.
"I have five kids who are missing out on their dad. I just want to go home, sir."
As Judge Davidson began going through the aggravating factors of the offending including the sustained nature of the premeditated attack, Wallace again piped up to offer his side.
"He was going to stab us, sir. He had a knife on him and he was going to stab us."
Wallace was given a discount on his sentence for his frankness by Judge Davidson, who gave him an additional 15 months imprisonment to be served on top of his existing sentence.
"I hope you are genuine and I hope you can deliver on what you have promised to us today."
Lawrence Taurerewa, a co-offender of Wallace who threw the first punch, also appeared for sentencing on a lesser charge of assault with intent to injure.
Defence lawyer Mark McGhie said Taurerewa had immediately shown remorse for his actions by trying to end the attack.
McGhie said Taurerewa couldn't change his past but could change how he behaves in the future.
Judge Davidson acknowledged Taurerewa's behaviour on the day.
"Although you initiated it, you had the decency and good sense to try and de-escalate it.
"Without your efforts to de-escalate it, things could've been much worse."
He noted none of the prisoners involved in the assault or the victim would co-operate with the authorities and the case was based on CCTV footage and prison officers' observations.
Taurerewa was committed to moving away from crime and finding out more about his culture, background and developing land his whānau received in a Treaty settlement.
Judge Davidson sentenced him to six months imprisonment to be served cumulatively on top of his existing sentence.