His lawyer Peter Tomlinson told the court the victim Tangi Nikoia was moved into his client's cell block on the day of the attack and immediately confronted him.
"It arose out of a comment made to him and a weapon shown," he said.
It all happened in Paremoremo Prison's infamous D-Block, which houses some of the country's most dangerous inmates.
CCTV footage showed the offender and his associate Lewis Isaaka tampering with the lock to the guard room, which the judge inferred was an attempt to stall their response.
They then entered the victim's cell, which was empty, before heading next door where they found him with another inmate.
The 31-year-old launched a frenzied attack against Nikoia punching him to the ground before repeatedly stabbing him with homemade "shanks".
While the victim lay in the fetal position, trying to protect his head, Isaaka warned the other inmate not to intervene.
"Don't try anything or you'll get stabbed up," he said.
Nikoia staggered out of his cell but was attacked again by the offender.
"Immediately after, you took off your shirt and walked across the landing with your hands in the air in something of a victory parade," Justice Patricia Courtney said.
Nikoia - serving a 16-year sentence for sexual and violent offending - was hospitalised with life-threatening injuries including a punctured lung.
"There was a lot of blood," the judge said.
The stabber got credit for attempts he had made in prison to see a psychologist to address his anger management issues but it could not save him from his new jail term being piled on top of his previous.
Justice Courtney said she understood "life in D block carries with it these kind of incidents more commonly than anyone would like" but it needed a stern response.
The stabber will be sentenced later this week.