Two vile inmates cornered a fellow prisoner so they could launch an attack.
Dylan Smith and Jethro Hardy cornered Lukasz Solarz on a landing in HMP Altcourse on June 20 last year before beginning to punch him and stamp on him.
Hardy even jumped up and landed on Solarz using his knees before he was dragged across the floor.
Smith, 26, appeared via video link for sentencing today, although his co-accused failed to turn up and is believed to be out of the country.
Fiona McNeill, prosecuting, first showed the court CCTV footage of the attack, after which Solarz suffered a split lip, lump to his head and pain in his back.
Ms McNeill said: "There are punches to the head, he fell to the floor both men kicked him on the ground.
"A prison officer can be seen running upstairs and coming to his aid."
Mr Solarz was then dragged across the floor to the railings.
Hardy attempted to continue the attack but was stopped by Smith from doing so, although the thug continued to shout at his victim, who has since returned to his home country of Poland.
The court heard how both defendants pleaded guilty to assault on June 22 prior to a trial scheduled to take place on July 22 this year.
In a number of magistrates hearings, Smith refused to come out of his cell.
Ms McNeill explained that Smith has 27 previous convictions for 78 offences.
Neil Gunn, defending, asked Judge Neil Flewitt, QC, to consider the offence as causing less harm as the injuries to Mr Solarz "weren't long-lasting".
Mr Gunn also asked the judge to consider the current conditions in prisons due to the coronavirus pandemic, which means prisoners are in their cells for 23 hours a day.
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He told the court that Smith attacked Mr Solarz after his victim threatened to stab him.
Mr Gunn said: "The defendant says, and it is not an excuse, that the complainant was known to be violent and had threatened to stab him."
He said due to the nature of prison that it's "not simply a question of keeping out of his way."
Mr Gunn said: "He took the decision to nip the case in the bud and had he not done so feels he would have been seriously injured himself."
Addressing the court before he was sentenced Smith said: "I want to start by saying I'm sorry for what I have done and I have taken steps to build a positive future.
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"I have done the Thinking Skills programme and the victim awareness booklet. It was a bad thing what I've done and I deeply regret it."
Judge Flewitt said: "That footage shows you and your co-accused, Jethro Hardy, surrounding your victim, Lukasz Solarz, one on of the landings in the prison.
"This is clearly planned to the extent that you approached him in different directions and trapped him at his location.
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"It shows both of you approaching at opposite directions and beginning to assault by punching.
"When he fell to the floor he was stamped on and your co-accused jumped on him and landed on him with his knees. He was then dragged to the railings at the edge."
"Fortunately your victim's injuries were relatively minor."
Judge Flewitt ordered Smith to serve an additional 20-month sentence on top of his current 55-months.
Smith will also pay a statutory victim surcharge.