An in-universe example are the unsuccubi who are so disfigured, physically and spiritually, from having their sexuality removed that just being in their vicinity causes normal succubi pain and terrifies all participates of the 3rd Arclent War.
He only appears late into chapter 4, but Tanurak is terrifying because of his complete inexplicability, and the terrifying implications of his existence. He's a Reality Warper who, even in a supposedly extremely weakened state, is capable of altering thought patterns and events through the Tower, where only a few extremely powerful beings are even capable of reaching him. He seems capable of causing a temporary Hate Plague that reaches even Yarra and Aka, and even cause people to lose restraint and kill, rape and riot if Simon isn't prepared enough to weaken him.
