Just to clarify, it sounded like the Child Hunts only started getting into gear when Julius had the throne and was possessed by Loptyr. Even if the tome was indestructible, it could still theoretically be placed in a chest and dropped off somewhere in the middle of the ocean, which has a similar effect to destroying it. It honestly seems like an easier way to the thwart Loptyr than forcing a girl to strike down her twin brother.