What spell did snape make up?

Snape didn't invent any spells, but he did create a powerful potion called "Elixir to Induce Euphoria." This potion, a variation of the Veritaserum truth serum, was designed to be a more refined and potent version that could elicit specific emotional responses. It was highly dangerous and could have serious side effects, leading to violent reactions.

However, Snape's primary contributions to the wizarding world lie in his extensive knowledge of potions and his role in creating the Half-Blood Prince's textbook. This book, with its annotations and innovative techniques, was a testament to Snape's brilliance in potion-making and his ability to push the boundaries of existing knowledge.

So, while Snape didn't invent a spell, his potion and his contributions to potion-making highlight his skills and influence within the wizarding world.