I came up with an idea as a fantasy world-building exercise which included a confusing book of spells, which if someone where clever enough to decode the centra

I came up with an idea as a fantasy world-building exercise which included a confusing book of spells, which if someone where clever enough to decode the central theme of the book, they would have performed the mental gymnastics necessary to cast a spell which would erase every possible future in which they did not become a supreme evil. But here the basic premise is that merely thinking the right thoughts can physically change reality. Which is 'sort-of' true for real brains, but there's an important layer of indirection that makes it not work the way I spelled out above.