A 16-year-old girl has been detained for life for the attempted murder of another girl at a fairground.
The girls roamed a funfair looking for a victim
The judge at Cardiff Crown Court told Shelley Farr that she would not be considered for parole before she had served at least four years and three months.
Judge John Griffith Williams QC heard she had an "unhealthy interest" in violent DVD films, and there was a risk of her striking again.
Farr appeared in court on Friday for sentence, following a hearing in December when the court heard that Farr stabbed a 14-year-old girl in a "frenzied attack", wounding her more than 20 times with a four-inch knife.
A 13-year-old who helped trawl the funfair for a victim with the older girl, acting as "bait", was found guilty of the conspiracy to wound, and was placed under a supervision order for two years and ordered to be tagged for 90 days.
"The girls hatched what can only be described as a bizarre plan that somebody was going to be seriously wounded," said Michael Mather-Lees, prosecuting.
"They trawled for their victim at a fairground and she was stabbed in excess of 20 times."
Mr Mather-Lees said Farr - who used a four-inch knife to carry out the stabbing - "intended to take a life that night. She meant to kill."
Passing sentence, Judge Williams said the case was "unique" in his experience.
"The two of you decided to seek out a victim with the express intention of wounding her.
"You picked out a victim for to attack, setting up what turned out to be a murderous assault with a knife.
"Your victim is scarred and may need cosmetic surgery. Her enjoyment of her teenage years has been seriously affected."
Turning to Farr, he said : "I consider you to be a manipulative young woman. I am not sure there's no risk of further offending.
"You told one psychiatrist you had an interest in watching DVD movies with violent themes. You are an unstable character and there is a likelihood of violent offending in the future.