’Styx and Stones may break my bones but words will never hurt me.’ Well, they will if you swear by the River Styx and then break your oath.
The River Styx goes through the Underworld and is in the charge of the Goddess of that name. She’s the daughter of the Ocean and had four children, Force, Might, Victory and Zeal who helped the Gods in the War against the TITANS.
She was rewarded with her own ten-channel river, a palace in the Underworld and dominion over the Oaths of the Gods. Anyone swearing such an oath has to drink from her ice cold waters to bind their vow. Quite a chilling experience as these drinks can freeze the blood and destroy mere mortals.