In "The Lost Hero" by Rick Riordan, a pivotal moment arises when a character confirms that "The Great Prophecy has begun." This declaration triggers chaos among those present, highlighting the significant weight of the prophecy and its implications for the characters' futures. It sets the stage for the unfolding adventures and challenges that lie ahead, impacting the dynamics within their world.

The revelation of the Great Prophecy acts as a catalyst for action, stirring excitement and uncertainty among the characters. The ensuing pandemonium reflects both the urgency of their situation and the high stakes involved, which are central themes in Riordan's narrative. The characters must navigate this new reality and confront the challenges foretold, ultimately shaping their destinies in this rich and engaging story.