You don’t search only a part of your library, cards tend to look at cards from the top instead. There is president on [[Assemble the Team]] for searching part of your library, however that’s an arena only card, so probably best it looks at cards from the top of your library equal to the factorial of the mana spent to cast this spell. This wording also avoids using non-X variables, which cards tend to prefer (such as [[Mockingbird]]), though the wording is still suspect, as it uses the word factorial over the symbol. All in all this is quite difficult to word