Back when Keth was going to be one of our PCs, I refused his player permission to break the "corebook only" rule, and after an extensive argument, I finally changed my mind and decided I'd allow the one spell he wanted, but he never responded to my last message. I feel as if, since my recalcitrance on the issue was some sort of dealbreaker issue for what was, in other respects, possibly the best character design anyone submitted for the game (no offense to anyone else, but some of the added details of the personality we discussed in PM were really cool insights), I sort of owe it to his memory to stick with the corebook-only hardline. Particularly since, if my public library ever reopens, I may have to return all my borrowed books. I might be able to do something about just the one adventure path book, or I could transition that campaign to something that only uses Monster Manual creatures and DMG magic items, but if a PC has a spell that I no longer have access to the text of, that could cause problems.