Level: MediumMass executing prisoners can quickly generate dread. Each execution will also cost 100 piety and decrease clergy opinion unless a prisoner is of a hostile or evil faith, or you have the Divine Retribution perk from the Torturer tree of the Intrigue lifestyle. No more than 10 prisoners should be needed. Also there are some traits that gain you more dread, such as Arbitrary, Sadistic, and Wrathful. A good start would be Rurik in 867. You can raid neighbor Rulers to get hostile prisoners and then execute them.
Credit to
Bayek von Kuwaq on Steam for his
guide.