When Hope's Light started to dissipate, Jack and Jeanny were ready to control their dragons to change direction following the herald. The dragons from their rune technique and mega spell had their own targeting system. They would home in on the enemy even if they were not controlled. But by exerting control, Jack and Jeanny could add feints and redirect the dragons to where they predicted the Herald might move. Thus, increasing the chance for the dragons to catch the target.
Jack was also ready to use his Void Displacement Eye to hold or move the herald into the dragons' pathway.
Unexpectedly, when Hope's Light imploded and the Herald was seen again, the Herald just stood there with an expression of agony.
"Did he fail to use his chaos armor in time?" Grace asked.