I'm not sure what your knowledge level of the inner workings of LLMs is, but a model doesn't need search or even an internet connection to "know" the information if it's in its training dataset. In your example, it's almost guaranteed that the LLM isn't searching books - it's just referencing one of the hundreds of lists of those spells in it's training data.

This is the LLM's magic trick that has everyone fooled into thinking they're intelligent - it can very convincingly cosplay an intelligent being by parroting an intelligent being's output. This is equivalent to making a recording of Elvis, playing it back, and believing that Elvis is actually alive inside of the playback device. And let's face it, if a time traveler brought a modern music playback device back hundreds of years and showed it to everyone, they WOULD think that. Why? Because they have not become accustomed to the technology and have no concept of how it could work. The same is true of LLMs - the technology was thrust on society so quickly that there was no time for people to adjust and understand its inner workings, so most people think it's actually doing something akin to intelligence. The truth is it's just as far from intelligence your music playback device is from having Elvis inside of it.