Many consider it the worst Dune book, but it's actually a great epilogue for the entire saga. Heretics of Dune takes place 1500 years after God Emperor of Dune's heavily built-up events.

Dune: Prophecy lays the groundwork for Denis Villeneuve's Dune trilogy and future adaptations of God Emperor of Dune ... power in Herbert’s penultimate book, Heretics of Dune.