Source, from the preview page about Liliana.
Amazon says 200 pages
It was leaked in the previews of this: https://www.amazon.com/gp/product/0744061059
They previews were changed, you can see them here: https://imgur.com/a/SqrmF8u
Some of the preview images on Magic the Gathering The Visual Guide had spoilers but have been taken down. Here's the gallery with spoilers.
It was here but the particular spoiler pages were pulled from the preview: https://www.amazon.com/Magic-Gathering-Visual-Guide-Annelli/dp/0744061059/ref=mp_s_a_1_1?crid=31OCJ5HRFHT20&keywords=mtg+visual+guide&qid=1658928559&sprefix=mtg+visual+gu%2Caps%2C662&sr=8-1
Here is where somebody preserved a screenshot of it and there is some discussion about it: https://www.reddit.com/r/MTGRumors/comments/w598u5/story_spoilers_in_image_preview_for_new_mtg/?utm_medium=android_app&utm_source=share
They must have changed it. I checked the preview pages just now, and I can't find any reference to unreleased sets. Instead, it just shows the same 6 pages twice. https://www.amazon.com/Magic-Gathering-Visual-Guide-Annelli/dp/0744061059/
It's called Magic the Gathering Visual Guide. Amazon goofed and has preview pages up on a book that comes out in December. It has at least 2 major major spoilers in the preview pages along with this one.
Oh sory ! I dont understand... This is my source :