He could fool them into believing that he needed to go to the City to be free of this restriction.
The basis of the lie was the truth.
"You were strong enough to defeat them? Do you want me to believe such stories?" the Mother Whale scoffed in response. "What proof do you have?"
"I don't have much of a proof, but I do have something that might make you believe me."
Karyk started taking off his clothes that he had tied around his wound to keep them hidden. This was the wound he received when he was fighting the Archangel.
It wasn't just the wound that was still left on his body. But there was also the essence of the Archangel that was mixed in that attack. So some traces of that were present as well.
"This is the wound I received in the battle. If you observe it closely, I am certain you can feel a trace of the kind of existence I was fighting."
