It was Kai's first-time hearing about making an oath.
He asked Matilda more about it, and according to her, this oath, which involved Zeus, is called the Soul Oath. Anyone who spoke an oath involving Zeus aloud would have their souls bound to that oath.
Breaking the oath would mean retribution.
And when it comes to Zeus, it would be death by lightning.
People, especially those on the surface, thought that death by Zeus' lightning would be quick.
But it wasn't entirely the case.
As the King of Gods, he has a reputation to maintain. His divine lightning would char every single nerve ending inside the person's body, and the process was quick to the eyes, but felt like an eternity for the punished person.
It was easily one of the most painful ways to die.
