Just say no to huge twist endings! (Esp the ones that involve hiding info from the reader)

When I read a book with a big twist ending, I'm usually impressed for ten minutes, and then I spend the next thirty minutes going, "Wait, if he was really on that side, then why did he do this? And why that? And how did this work?"

A book with a big twist ending has two masters: it needs to support the OSTENSIBLE reading (the one it wants you to believe …