He played a crucial role in the Battle of Algul Siento. Under Roland Deschain's orders, he planted sneetches under several of the buildings. These sneetches were set to explode at the same time and contributed to the confusion of Algul Siento's guards.
Haylis was almost caught by Pimli Prentiss and Finli O'Tego. He was stopped and questioned about the basket he was carrying. He was only carrying used tissues, items that are considered delicacies amongst his people.