An Unbreakable Vow is a magical spell of unknown incantation, in which one wizard or witch makes an oath to another. If either of the wizards break their terms, they die.
Casting and effects[]
The Vow is cast by having two wizards facing opposite each other and clasping their right hands. A third wizard must hold their wand, standing quite close to the pair holding hands, and place the tip of their wand onto the linked hands, as Bonder. Then, the first will ask a certain number of vows of the other, with the second accepting those terms; it is unknown what happens if he or she declines. Each time a term is accepted a thin stream of fire will be emitted from the Bonder's wand, weaving around the hands of the pair taking the vows.