Stygian Oaths

Stygian Oaths are the greatest and most dreadful oaths that can be made. Any oaths sworn on the waters of the River Styx are divinely binding, even to the Gods. A Stygian Oath can not be broken under any circumstance, including death.
Stygian Oaths are enforced by the Goddess Styx, the personification of the River Styx. She was made the agent of oaths by Khronos as a reward for unknown reasons.
Because of the nature of Stygian Oaths they are rarely made for risk of unforeseen complications.