Without a word, Izelda sent one of his companions, a well-muscled pirate, after him. The man drew his sword and moved to attack the boy, but the moment he ran forward, he fell onto his face and stopped moving. He was dead, but Izelda had no idea how.

“Interesting.”

He was impressed by the existence of such a power. He had thought that even if the other vessels had failed to understand, he might be able to figure it out if he saw it firsthand. He knew that the boy was responsible. If he paid close attention, he should have been able to at least catch a glimpse of his actions, even if it was nothing obvious. But he couldn’t pick out anything. The boy wasn’t using the Gift, and there was no apparent use of magical energy. Without any warning, the vessel’s heart had simply stopped. That’s all he could tell.

-Volume 6 pages 184-185