Wandcores

A wandcore is the magical substance placed within the length of a wand. This core is the primary channel for the wand's power, and its specific properties, in combination with the wand wood, determine the wand's unique character and temperament. The renowned wandmaker Garrick Ollivander believed that the selection of a high-quality core was essential to the creation of a superior wand, leading him to exclusively use what he termed the “supreme cores”. The interaction between a wizard or witch and their wand is heavily influenced by the nature of its core, underscoring the principle that “the wand chooses the wizard”.

Garrick Ollivander built his family's reputation on the principle of using only three specific, powerful substances for his wandcores. He considered all other materials to be inferior for producing wands of the highest quality.

• Dragon heartstring: Wands with this core are known for producing the most raw power and are capable of the most flamboyant spells. They tend to learn more quickly than other wand types. While they can change allegiance if won from their master in combat, they bond strongly with their current owner. Of the three supreme cores, dragon heartstring is the most easily turned to the Dark Arts, though it will not do so of its own accord. Notable wands with this core belonged to Hermione Granger, Lucius Malfoy, and Peter Pettigrew.
• Unicorn hair: This core is known for producing the most consistent and reliable magic, being the least subject to fluctuations and blockages. Wands with unicorn hair are the most faithful to their original owner and are the most difficult to turn to the Dark Arts. A minor drawback is that they do not typically make the most powerful wands (though the wand wood can compensate) and are prone to “melancholy” if seriously mishandled, meaning the hair may die and need replacing. Ron Weasley's first wand (inherited from Charlie Weasley) and Cedric Diggory's wand both contained a single hair from a male unicorn.
• Phoenix feather: The rarest of the three supreme cores, phoenix feather is capable of the greatest range of magic, though it may take longer than other cores to reveal its full capabilities. These wands often show the most initiative, sometimes acting of their own accord, a quality some wizards dislike. They are extremely particular about their owners and their allegiance is hard-won. The wands of Harry Potter and Lord Voldemort were “brothers,” as both contained a tail feather from the same phoenix, Fawkes.

While Ollivander was dismissive of them, other wandmakers have successfully used a variety of magical substances as cores.

• Veela hair: This substance is known to produce “temperamental” wands. Ollivander refused to work with it due to its volatility, which he felt detracted from the quality of the instrument. The wand of Fleur Delacour contained a single Veela hair from her grandmother's head.
• Thestral tail hair: An extremely potent but unstable substance, the tail hair of a Thestral can only be mastered by a witch or wizard capable of facing death. It is the core of the Elder Wand, one of the three Deathly Hallows, and is likely responsible for the wand's immense power and treacherous allegiance.

The wandcore is central to a wand's identity and its relationship with its owner. The most significant example of a core's unique magical properties is the connection between wands with cores from the same source, known as “brother wands”. When Harry Potter and Lord Voldemort duelled in the Little Hangleton graveyard, their wands, containing twin phoenix feathers, refused to fight each other properly. Instead, they locked in a golden beam of light and initiated Priori Incantatem, forcing the victim's wand (Voldemort's) to regurgitate the spells it had recently performed in reverse order. This phenomenon saved Harry's life and was a direct result of their shared wandcores.

J.K. Rowling greatly expanded upon the lore of wandcores on the Pottermore website (now Wizarding World), introducing a wider variety of materials used by wandmakers outside of Great Britain.

• American Wandcores (Pottermore): The four major American wandmakers of the 20th century each favored a different core native to North America.
  • Thunderbird tail feather: Favored by Shikoba Wolfe, these cores create powerful wands that are good for Transfiguration and can sense danger.
  • Wampus cat hair: Used by Johannes Jonker, this core makes wands that are powerful, fast, and difficult to master.
  • Horned Serpent horn: Favored by Thiago Quintana, slivers of the horn are used in wands that are exceptionally powerful and sensitive to Parseltongue.
  • Rougarou hair: Used by Violetta Beauvais, this core is strongly attracted to the Dark Arts.
• Other Cores (Pottermore):
  • Basilisk horn: The wand of Salazar Slytherin contained a fragment of Basilisk horn as its core.
  • Troll whisker, Kelpie hair, and Kneazle whisker have also been used by lesser wandmakers, though Ollivander considered them to be of inferior quality. (Pottermore)