"As a bonus, [Batman #85] also features a prelude to "Their Dark Designs,' the new epic written by James Tynion IV that gets under way in Batman #86 and touches on the revelation of Superman's secret identity!" reads DC's description.
"This two-page sneak peek, guest starring the Joker, features art by Guillem March, and sets the stage for what's to come in 2020!"
Described as a "bonus," this added prelude will not change DC's planned 48 page count.