- “It's an archaic exercise in cruelty. Locking her in this tomb… Weakened, defenseless… Unleashing that on her.”
- ―Rupert Giles[src]
Tento di Cruciamentum was a rite of passage practiced by the Watchers Council to test the Slayer whenever she lived to see her 18th birthday. While some of the more conservative members of the Council considered it a time-honored rite of passage, other less ruthless Watchers considered it to be a brutal, antiquated practice, Rupert Giles describing it as an "archaic exercise in cruelty."
- “It's a test, Buffy. The Tento di Cruciamentum. It's given to Slayers when they reach— if they reach their eighteenth birthday.”
- ―Rupert Giles[src]
In the weeks prior to the Slayer's 18th birthday, Watchers were charged with injecting the Slayer with chemicals, such as muscle relaxants and adrenaline suppressors, which gradually weakened her powers until she had the average physical abilities of a human, if not even weaker. Watchers were also ordered to keep the Slayer unaware of the test, using hypnosis so she wouldn't notice the injection. Afterward, the Slayer would be taken to a location selected by the Council and pitted against a particularly dangerous vampire. The intent of the practice was to establish the Slayer's intelligence and practical capabilities, testing her ability to out-think her enemies as well as outfight them.
While students at the Watchers Academy, Watchers-in-training would also endure a similar test of abilities, dispatched to deal with a certain vampire. Although, they wouldn't suffer a loss of power, would be aware of the test, acted in group, and members of the Council would observe closely to interfere whenever there was any danger to the students' survival.
The Slayer Nikki Wood was pregnant during her Cruciamentum, in 1973. Her Watcher, Bernard Crowley, objected to making her endure the ritual in this condition, but she insisted on participating, which she did despite her knowledge about the test. While being sorely observed by her own Watcher, Nikki successfully staked the vampire at the top of a building. Afterwards, she noted that, despite cornered by the vampire, the creature threatening her unborn child that gave her strength to defeat him.
In 1999, Buffy Summers was pitted against Zachary Kralik, a psychotic vampire who, in life, had been a serial killer who tortured and murdered young women. However, the test was jeopardized from the beginning due to various factors. Kralik escaped captivity, siring one of the Council employees assigned to monitor him (Blair), while killing the other (Hobson). He then abducted Joyce Summers, the Slayer's mother, taking her to Sunnydale Arms so Buffy would come to him for the Cruciamentum. With this, her Watcher Rupert Giles finally revealed to Buffy about the test with the intention of cancelling it, since the Slayer was supposed to be kept in the dark about it.
With her own mother's life at risk, Buffy went after the vampire anyway, and was eventually able to defeat him by taking advantage of his reliance on painkillers. She switched the water he took with his pills with holy water, causing him to burn up from the inside. Though Buffy was successful, Giles was ultimately dismissed from the Council for his interference in the Cruciamentum and for his display of emotional attachment to Buffy.