"And Your Majesty must be especially careful, for these three Sirens... must never be released simultaneously."
Chiron warned, "The power of any single Siren by itself has its limits... which is bounded by 'the furthest reach of its voice.' Their strength wanes from the center to the fringes, so if the White Lady loses control, she will merely submerge the capital in water.
"But if the three Sirens exist at the same time and sing together, they will activate the apocalypse protocol. Their voices will then spread across the entire world."
It would be the ultimate world-ending mechanism, reverting the heavens and earth to their primordial state, utterly destroying the world.
By then, the majority of the gods would perish with it.