A teenager used a dagger-type knife in his clenched fist to repeatedly stab a good Samaritan in the head hours after a Merseyside derby.
Wayne Lee, 19, was high on cannabis and ketamine as he and a group of friends scoured Liverpool city centre looking for violence.
The Kensington man came across 18-year-old Scott Sheerin who was trying to help a group of drunk girls who were sat on the kerb, near Concert Square.
Mr Sheerin tried to get the group of girls water from a nearby bar, but when he returned one of Lee's friends confronted him, possibly grabbing his neck or cutting his neck with a blade.
A student, whose flat balcony overlooks the scene, witnessed the attack, and told police she heard Mr Sheerin shout, 'he's just held a knife to my throat!"
One of the gang, annoyed by the victim's objections, punched him in the face, and he collapsed, hitting his head on the floor, Liverpool Crown Court heard.
Lee, at this point, joined in the group assault, as Mr Sheerin was kicked three times to his head, until he was unconscious.
The victim suffered a broken nose, bruising to his jaw and concussion, but remembers little about the vicious beating on Fleet Street, at about 2.30am on December 5.
Jakub Klaur, the second victim, was walking past the scene, and witnessed Mr Sheerin being attacked.
The 24-year-old good Samaritan pointed to Lee, and tried to grab his top, but that enraged the 19-year-old who produced the dagger out his pocket, wielding the weapon like a knuckleduster.
Mr Klaur was knocked to the ground where he was stabbed repeatedly to his head, Christopher Hopkins, prosecuting, said.
Shocking CCTV footage of the assault was played in court, as the barrister pointed out the "one, two, three, four stabbing blows."
The victim suffered stab wounds to his chest, left of his spine, three wounds to his temple and side of his head.
The short 1.5 inch blade probably meant Mr Klaur did not suffer more serious injuries, it was heard.
It was previously reported that an heroic doorman from the nearby Black Rabbit bar ran over to break up the fight.
A constable who arrested Lee, who at first acted as a "peacemaker", described him as under the influence of drink or drugs, slurring his words and with glazed eyes.
Michael O'Brien, defending, who described his client as "somewhat immature", convinced Judge Denis Watson QC that Lee should not be classed a "danger to the public."
The barrister, who said the stabbing lasted for 20 seconds, claimed Lee was "thoroughly ashamed of his actions" and had "genuine remorse."
Lee, of October Drive in Kensington, who has "limited convictions" and is experiencing his "first taste of custody," had applied for enhanced status behind bars and was studying maths and English courses, it was added.
Judge Watson told him: "You were out in Liverpool city centre armed with a knife, described as a push dagger, a small but very unpleasant looking knife, to be held in a clenched fist so the blade protrudes behind the fist, of 1.5 inches, akin to the way a knuckleduster is used.
"You were spoiling for a fight...looking for trouble."
Lee, who admitted causing grievous bodily harm with intent, possession of a knife and actual bodily harm, was jailed for six years.
He waved to family members as he was sent down.
