Kai's attack was so swift and fast that no one out of the three devouts could react in time. After all, they had never seen this attack from Kai before.
Divine Departure is a one-slash attack that deals devastating damage to the target no matter what it is. Kai had been training it in secret for a long time using Wretched without the surveillance of the people who trained him.
Ever since the start, Kai has never trusted anyone around him at all. He knew that what they were doing was no good but he didn't bother to try and stop them since he wanted nothing to do with this kingdom of weird people.
That was why he decided to start developing his trump cards in case things went south and he had to fight against his father and his Devouts. That's where he began to unravel the mysteries surrounding Wretched Heart and its hidden powers.
When he finally discovered what this cursed sword could do, Kai knew that he needed to hide that from everyone else.
