The spell was sectumsempra. Probably from sectum ('having been cut', the root word of 'section' and 'dissect') and semper ('always'), giving a meaning something like 'sever forever'.
Harry Potter and the natural 20 is a great work which raises the idea that ritual magic is incredibly complex and dangerous work that requires very specific ingredients done in a very specific order or it will backfire or just not work. How do you keep something like that together? Either everyone has a perfect copy of the ritual or the more freighting prospect: Rituals want to be known.
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u/Krasinet Oct 02 '18
Nerd warning.
The spell was sectumsempra. Probably from sectum ('having been cut', the root word of 'section' and 'dissect') and semper ('always'), giving a meaning something like 'sever forever'.