Just as breaking through to the Earth Sovereign Realm requires heaven and earth to send down a tribulation, breaking through the Heavenly Sovereign barrier will inevitably trigger one as well.
This tribulation is known as the Heavenly Sovereign Tribulation.
It is an extremely terrifying ordeal. To say nothing of those who have yet to truly step into the Heavenly Sovereign Realm, even genuine Heavenly Sovereigns would view it with deep apprehension.
Chapter 564