I'd written a post about this on my phone - pics and everything - but the Blogger app for Android is very unstable and completely melted down when I tried to publish. I had to forcibly restart and do all kinds of things to even erase the faulty post. Piece of rubbish.
So I'm just going to note that I read this and well it's a Pratchett and I enjoyed it. This is the one where the heir to the Faraonic throne is educated as an assassin before having to return to be king. Pyramids - cosmic energy - time - kaboom. There.