The term «Oath» is used for the ritual where elementalists exchanged vows. It was quite commonly used when exchanging important promises. If an elementalist were to break the «Oath», that person would suffer harsh punishment. For example, they would be viewed as an enemy by the spirits and be cut off from the blessing of the leylines for a long term. Depending on the severity of circumstances, they could even lose the power to summon contracted spirits.
A kiss from both parties is necessary to establish an «Oath».
«Oath» were exchanged in composed spirit language
"In the name of the Elemental Lords I hereby swear. Even if the heavens collapse and the earth splits open--"
"The contract we hereby exchange shall never be breached. Or else--"
"I shall be incinerated in eternal conflagration, until my shadow turns to ash--"
Trivia
- There were no rules about the location of the kiss. For instance, the Oath between Milla and Kamito, while Milla kissed him on the cheek, Kamito kissed on the back of her hand.