Unbreakable Vow at Spinner's End• Event
Snape and Narcissa take the vow together, with Bellatrix serving as Bonder. Snape agrees to help Draco with his task and to finish it for him if Draco fails (HBP2). Read More
— "wand actions and vow seal the magic"
The Unbreakable Vow creates a magically binding vow between two people. The spell apparently cannot be performed using wandless magic (judging from Snape’s remarks to Bellatrix rather than from the Weasley twins’ underage efforts) and requires that the Bonder’s wand be touching the joined hands of the person administering the… Read More