Such was the severity of the assault, officers found large amounts of blood spatter on the walls and ceiling of the address, the Dunedin District Court heard.
Robinson and Holmes-Larsen each pleaded guilty to injuring with intent to do grievous bodily harm and were locked up at the end of last year.
The former was jailed for 25 months and will have to serve every day of the sentence, after receiving his first strike for a similarly violent street attack in 2016.
Holmes-Larsen, who was also sentenced on driving charges, got three years, three months.
Mark, who had never met his assailants, remembered hearing the raised voice of his female flatmate and went to investigate.
He said he told the duo to "bugger off" — then his recollection becomes murky.
"It's all a bit of a haze," Mark told the Otago Daily Times.
"It's wee flashback moments. I think my mind is just trying to block it all out."
The extent of the viciousness, however, was revealed in court documents.
Robinson and Holmes-Larsen had been told by the woman at the house that she did not have any cannabis to sell them.
When Mark intervened, their wrath had a new target.
First, Holmes-Larsen threw the victim into a mirror, causing it to smash. Robinson then held him by the arms, allowing his mate to hit the defenceless man several times in the face.
The attack continued while the woman locked herself in a nearby bedroom and called police.
Mark broke away from the defendants but his respite was brief as they chased him into the hallway and continued to hit him in the head and body as his blood sprayed around the area.
It carried on for several minutes as the victim staggered into a spare room.
When Robinson and Holmes-Larsen were later interviewed by police they admitted being responsible and said "it went too far".
Mark's list of injuries was evidence of that.
He had multiple haematomas to his face, a fractured eye socket that caused the eye to swell shut and a 9mm laceration to his kidney.
If officers had not rushed him to hospital, he would have needed a blood transfusion, doctors said.
More than a year on from the incident, Mark said he was still plagued by the consequences.
His kidney was still healing, there were headaches, he had night terrors and paranoia, depression and anxiety, which he had never experienced before.
Simple maths and spelling had become a struggle and Mark was unsure yet whether his damaged teeth would die.
"All I think about is it could have been a lot worse," he said.
At sentencing, the court heard of the disadvantaged upbringings of the defendants.
Robinson endured a "disaster of a childhood", being deprived of the necessary nurturing and structure. It was a similar story for Holmes-Larsen who was kicked out of school at 13 and never returned.
While the pair would be behind bars for some time, Mark remained nervous about being targeted by them again.
"I just hope they pull their heads in," he said.
*Name changed to protect the victim's identity
