Ciarán Murphy (29) was stabbed 16 times in his Co Offaly cottage and set on fire after his ex-girlfriend spread a false rumour that he was a garda informant.
He was found in a dog cage in the house by a passer-by who spotted the house was in flames.
Mr Murphy was left with life-threatening injuries after he suffered 96pc burns from his neck down and multiple stab wounds, including into his heart cavity.
He continues to suffer bleeding from some of the wounds that cover his body, Dublin Circuit Criminal Court heard.
In a victim impact statement, he said the attack destroyed his life and he sometimes wishes he had not survived.
David Keena (21) was 17 when he went with an older co-accused, Shaun Groome, to Mr Murphy's house.
He was present when Groome stabbed the victim and poured petrol over him, the court heard.
Keena, of Carrig Mor, Mullingar, Westmeath, pleaded guilty to assault causing serious harm and criminal damage by way of arson at Mr Murphy's home at Coolcor, Rhode, Co Offaly, on September 7, 2015.
Describing his culpability as lower than that of his co- accused, Judge Karen O'Connor sentenced Keena to six-and-a half years with the final 18 months suspended.
She said Keena had no other convictions at the time, but noted that he is serving a partially-suspended six-year prison sentence imposed in July last year at Mullingar Circuit Criminal Court for a drug dealing offence.
The sentence imposed yesterday will run consecutive to that one.
Anne Rowland, defending, said her client was accepting responsibility on the basis that he aided and abetted Groome (31), who has an outstanding warrant out for his arrest.
Groome, of Ballinderry, Mullingar, Westmeath, was charged in November 2015 with assault causing serious harm when he appeared at a sitting in Tullamore District Court.
Judge O'Connor said Keena involved himself in horrendous behaviour on the night and noted the attack was pre-meditated.
She said the mitigating factors were that at the time Keena was very young and had no previous convictions.
The judge added that he was abusing drugs, and on the night of the attack he was on a cocktail of cocaine and vodka.