Sectumsempra (creator: Severus Snape) was a curse used to slay or kill a person. This deadly curse was

The effect of sectumsempra

created by Severus Snape to use on the Marauders during his school years at Hogwarts School of Witchcraft and Wizardry. The curse's effect is basically as though the victim had been mercilessly slashed by a sword. Sectumsempra works only on living targets, as Inferi are not affected by it at all.
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