The horn of a Horned Serpent is a wand core used by Ilvermorny founders James Steward and Isolt Sayre in the 17th century when they begun making their own wands. Horned Serpent horn wands are exceptionally powerful. They also are sensitive to Parseltongue and warn their owner of danger by emitting a low musical tone.
Isolt had promised Chadwick Boot a wand when he turned eleven. The evening before his birthday, she received a dream in which she went down to the creek to visit the Horned Serpent she had befriended years earlier which rose up out the water and allowed her to take a long shard of its horn when it bowed its head. Isolt then woke up and went to the creek where the Horned Serpent let her do what she had done in her dream. She took a shard of the horn and returned to the cottage where she asked her husband James who was a skilled craftsman to make a wand from the horn. He set it in a wand made of ash wood which had exceptional power. The only other known owner of a wand made of the horn of the Horned Serpent is Webster Boot whose wand was also made by Isolt and James. They had chosen to reserve the core for just Chadwick and Webster and only made other wands of other cores.
- Pottermore (Mentioned only)