"It is a crime that is so cruel, so horrific, that in our submission the offender is not deserving of the court's mercy," prosecutor Jane Warren told the Supreme Court in Melbourne.
Patterson faced an emotional hearing on Monday where several family members of her three murder victims - Don and Gail Patterson, 70, and Heather Wilkinson, 66 - gave statements about the impact of her crimes.
Justice Christopher Beale described the mark of the murders and attempted murder on Patterson's victims as "a tsunami" that had affected four generations.
Sole surviving lunch guest Ian Wilkinson offered his forgiveness to the 50-year-old for trying to kill him, and asked her to confess.
But she continues to maintain her innocence.
Patterson's lawyers accepted she will be handed a maximum sentence of life in prison for serving up a toxic beef Wellington to her estranged husband's family.
"We make no argument the head sentence should be anything other than life imprisonment," her barrister Colin Mandy SC said.
He argued even if Patterson was given a non-parole term of 30 years, she would be almost 80 if she was ever to get released.
Mr Mandy cited her conditions while behind bars, where she has been held in isolation with limited access to the outside, as among the factors in permitting a fixed non-parole period.
She has been held in a separate isolated unit due to her "notoriety", which Mr Mandy said would not likely diminish anytime soon.
He also claimed her purported Aspergers syndrome had made it difficult for her to cope behind bars.
"She does find it difficult because of that condition because she finds it difficult to cope with changes in routine," Mr Mandy said.
Mr Wilkinson described the impact of losing his wife Heather and becoming ill, while offering an olive branch of forgiveness.
"Erin has brought deep sorrow and grief into my life and the lives of others," he told the court.
"In regard to the many harms done to me, I make an offer of forgiveness to Erin."
The church pastor, 71, urged Patterson to offer a "full confession and repentance."
"I bear her no ill will, my prayer for her is that she will use her time in jail more wisely to become a better person," he said.
"I am no longer Erin Patterson's victim, and she has become the victim of my kindness."
Patterson appeared to become emotional as Mr Wilkinson spoke, holding back tears from the dock.
Mr Wilkinson grabbed tissues as he described a loving relationship with his "compassionate, intelligent, brave, witty" late wife Heather.
"It's one of the distressing shortcomings of our society that so much attention is showered on those who do evil, and so little on those who do good," he said.
His daughter Ruth Dubois described the trauma the murders, subsequent trial and media attention had brought to her family.
"On the 29th of July, 2023, four generations of our families - ranging from newborn to 99 years old, countless friends and the wider community - were handed a lifetime of carrying this unimaginable horror," she said.
She said it was "difficult to comprehend" how Patterson had spent time planning and preparing the deadly meal, knowing the "tremendous harm" it would cause.
"But instead, at every step of the way she chose to follow through."
Ms Dubois said it had been "particularly revolting" their family tragedy had been used as "entertainment for the masses".
Simon Patterson said his estranged wife had "robbed" their two children of their grandparents, and now they must face what she had done, in a statement read to court.
Patterson was on July 7 found guilty by a jury of three murders, and the attempted murder of Mr Wilkinson, over a death cap mushroom-laced beef Wellington lunch in July 2023.
Justice Beale said he will sentence Patterson on September 8.
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