Victorian Supreme Court Justice Terry Forrest said Luke Wentholt, 31, had behaved, according to one witness, like a "crazy monster".

Wentholt, who had previously been jailed for bashing and robbing a prostitute, pleaded guilty to the murder of David Greene, 30, and one count of recklessly causing serious injury to David Byas, 29.

Wentholt had been drinking beer, vodka and whisky and smoking cannabis, and was showing off karate and ju-jitsu moves before repeatedly stomping on the heads of Mr Greene and Mr Byas at the boarding house on August 26 last year.

Mr Greene died in The Alfred hospital on September 7.

Justice Forrest said Wentholt's criminal history dated back 13 years and involved convictions for assault in Western Australia, South Australia and Queensland.

"You have led a violent adult life with little regard to the rule of law and wellbeing of others," the judge said.

"I regard the need to deter you and to protect others from you as relevant factors in this sentencing exercise."

Justice Forrest said he had listened to and read the victim impact statements from Mr Greene's family and friends.

Vision from the courtroom and the judge's comments were streamed live over the internet to a home in Dublin for Mr Greene's family to watch.

"David Greene's family has lost a much loved young man," the judge said. "Their grief is compounded by the mindless violence that accompanied his death.

"His death was unprovoked and totally unnecessary."

Wentholt was jailed for 18 years and six months with a non-parole period of 15 years.

He showed no emotion as he was led away.

Justice Forrest said it had been about 1am on August 26 when Wentholt told Mr Greene he wanted to speak to him outside. Mr Greene had been joking about walking in on Wentholt's then girlfriend, Shayla Pullen, days earlier when she was naked in Wentholt's bed and he saw her breast.

Party guests heard raised voices and loud banging noises before Mr Greene and Mr Byas were found lying unconscious on the hallway floor.

In her police statement, Ms Pullen said: "There was blood everywhere."

She yelled: "What the f--- are you doing?" to the bare-chested and barefooted Wentholt when she saw him stomp on Mr Greene's head.

Mr Greene, a bricklayer, had travelled to Australia in January 2011 for a better life because of the recession in Ireland. He spent time in Perth before moving to Melbourne in January last year.

He became manager at the Lynedoch Avenue boarding house, making sure the property was clean and collecting rent from tenants.

Mr Green's parents and their two other sons were by David's bedside when his life support machine was turned off at 8pm on September 6. He died at 3.05am the next day.

In her victim impact statement, his mother, Catherine, said she could not imagine ever being happy again after her son's death. She would never forgive Wentholt for what he had done.

And David's father, Aidan, said he would always feel guilty for lending his son the money to come to Australia.

Mr Byas, who was in an induced coma for five days before recovering in hospital for six weeks, is expected to recover after returning to Ireland but has not yet been able to return to work as an electrician.

In his victim impact statement, Mr Byas said after his release from hospital that he had tried his hardest to pretend everything was fine and that he had not been affected by what had happened.

"As time has gone on, I have come to the realisation that it is completely impossible to go through something like this and not be seriously affected," he said.

"This will impact my life forever and there's no escaping that fact. I feel like I will have serious trouble trusting people again.

"I feel like I've been sheltered from pure evil my whole life and now that I have been exposed to it, things can never be the same. I lost a very close friend in Davie and that completely eats me up inside. And for what?

"I just don't think it's fair at all what happened to us. We were the last two people that deserved this and it makes me absolutely furious."

Mr Byas said he had been in Australia about six months before crossing paths with Wentholt and it was the most beautiful country he had seen.

"I also met such friendly people over there, some of whom I would consider friends forever. Unfortunately, now when I think of Australia I just think of evil, heartache and sorrow."