At the end of "Something Rotten", Yorrick Kaine and the Unitary Authority of Warrington Cat have a duel where they invoke creatures from books to fight for them. There's only one rule - no Krakens.
I'm wondering why Kaine didn't invoke the Questing Beast? We know that he can, because he's done so in an earlier book. The only person who can defeat the Questing Beast is Sir Pellinore, who is fated to always appear after the beast is already gone. It would have been an easy win. In fact, when the Cat started to talk about rules, I expected that the Questing Beast would be disallowed. Him disallowing the Kraken came as a surprise, especially since the Kraken hadn't even appeared in the series at that point!
So... what kept him?