Lisa Anne Perryman, 56, is on trial after her late husband Neville Perryman's alleged attack on Horace Reginald Peter Monshing in regional southern Tasmania in November 2020.
The Perrymans had both pleaded not guilty to two counts of committing an unlawful act intended to cause bodily harm as well as assault.
In opening submissions on Tuesday, crown prosecutor Julianne Greenwood said Mrs Perryman was criminally responsible despite not wielding the chainsaw.
Ms Greenwood said Mrs Perryman abetted and encouraged her husband, who died in 2022, to carry out the alleged attack.
The Perryman's dog had caused tensions leading to Mr Monshing making a formal complaint to council, the prosecutor said.
It resulted in an "escalation" in which the Perrymans drove their car to Mr Monshing's neighbouring Middleton property at night after drinking alcohol.
Mr Perryman walked up the Monshing's driveway with an operating chainsaw, while Mrs Perryman drove the car behind him with headlights on.
The court was told Mr Perryman swung the chainsaw towards Mr Monshing's head, connecting with his forearm and later his hand.
Mrs Perryman allegedly said "I want him dead", "I want the dog to rip his throat out" and "I want you dead, your wife dead, your daughter dead and granddaughter dead".
Mrs Perryman said she would get her brothers to "finish the job", the Supreme Court of Tasmania was told.
Mr Monshing told the court he defended himself with a wooden croquet mallet he had made during COVID-19 restrictions.
"(I had my) arms up trying to stop the chainsaw from cutting my head off," he said.
"I knew I had to fight for my life. I drove him backwards with the mallet ... away from the house."
Mr Monshing said the Perrymans' dog was biting his legs during the altercation. He was left "very, very heavily" bleeding and taken to hospital.
He denied suggestions he had previously blocked the driveway to the Perrymans' house.
He admitted previously throwing things at the dog because he didn't want it biting his family.
Ms Greenwood said the Perrymans had formed a common purpose to commit the crimes.
She said Mrs Perryman had driven her husband to the Monshings' property, tried to push Mr Monshing over and screamed things.
The assault charge relates to several punches allegedly inflicted by Mr Perryman to Mr Monshing's head.
The trial continues.
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