Harry Potter: 10 Worst Things Snape Ever Did

During his teen years, Snape excelled when it came to potion-making and the dark arts. Yet he was more than just a smart student – he also invented his own magic.

The deadliest spell Snape invented was – without question – the Sectumsempra Curse. This dark piece of magic causes large gashes to erupt across the victim’s body, leading to excessive bleeding.

How and why Snape invented this spell isn’t clear – Rowling doesn’t give any details. But only a deeply disturbed individual would create such a curse.

Thankfully, Sectumsempra is only used twice throughout the series. Harry uses it on Malfoy in The Half-Blood Prince and Snape himself uses it in The Deathly Hallows. Given the devastating effects of the spell, it should really be classified as a fourth Unforgivable Curse.