What is Jason's Prophecy?

Jason's prophecy is a poem given by Rachel Dare at the beginning of the story to help the heroes on their quest to free Hera. It suggests that freeing Hera will bring death, which proves to be true as she appears in her godly form and kills Jason by mistake. Thankfully, Piper brings him back from death. The line about the forge and the dove means a child of Hephaestus and a child of Aphrodite will have to work together, which of course refers to Leo and Piper. The prophecy is: "Child of lightning, beware the earth/The giants' revenge the seven shall birth/The forge and dove shall break the cage/And death unleash through Hera's rage." (Chapter 10, Piper, p. 126).