In the center of each wand is a core taken from a plant or animal that is believed to hold mystical powers. This is what gives wands the oomph to channel magic through them. In some cases, wands may have two cores, called a "dual core", though usually the second core is drastically less powerful than the first core. The use of a second core is often to make up for what the first core lacks. Some cores cannot be blended or paired with another. Examples of this is veela hair. Dragon heartstring has also been shown to disagree with many cores. Unicorn tail hair, in comparison, is often open to sharing a wand with another core.
An Ashwinder Egg emanates intense heat before it is born, and most Ashwinder eggs hatch very quickly after they are laid. The eggs are rather valuable when made into wand cores, but the precision and timing to convert this ingredient into a magical core makes it rather expensive. However, with difficult tasks comes a great result. Ashwinder Egg cores allow great magical leeway for many Conjuration spells – extremely useful for Wizards keen in Transfiguration.
Whilst the Basilisk Fang is known to be extremely venomous, the scales of a Basilisk are extremely valuable as well. When converted into a wand core, the scales provide a nice finishing boost to a wide array of spells. It prefers Curses and Hexes, not surprising. It’s a favorite of Dark Wizards, and its rarity on the market makes Basilisk Scale wands rather hard to get your hands on. Due to the affluence many Slytherin pureblood families have, a Basilisk Scale can be considered a nice treat for their wands if they can purchase it in the first place. Basilisk scales also respond strongly to Parselmouths.
The brilliant sapphire-blue shells of the Billywig beetles are greatly favoured as wand cores, due to the magical properties found in its aramid-like compound shells when crushed in a mortar. Billywig shell cores make casting spells very fast and easy, and they are very common amongst Ravenclaws for their speed, light weight, and general ease of use.
One of the most common wand cores in the Wizarding World, dragon heartstring is greatly favoured for its potency and power in casting strong spells of any category. Due to its stability to cast almost all categories of spells rather effectively, it is greatly favoured by wizards that have a strong grip and control over their own magic to utilize this core to its fullest potential.
Though relatively weak, Fairy wing is great for charms - that's actually its strongest power. However it usually fails at hexes and isn't very good at casting offensive spells, making it a more support oriented wand core. Fairy wing wands genereally only bond with Seers, those who possess "the sight".
Grindylow teeth are now harvested for wand making after they were found to possess magical properties. Grindylow wands are described as rough, brittle, but very sharp and focused. While they don’t produce very fantastic results for any sort of magic, they are greatly favoured by powerful Wizards for their aim. Grindylow tooth wands have this certain precision for hitting their target on mark, lowering the chances of misfiring a spell.
Very close in properties to the dragon heartstring core, Hippogriff talons are used for their power and raw ferocity. They are normally combined with strengthening wood to further strengthen spells that are casted – usually destructive in nature – and are heavily prized by Dark Wizards for their distinctive, powerful ambience. However, they aren’t very compatible with timid, unsecure people. Only those who are confident in themselves can use wands with this core effectively.
While kneazles are often breed as familiars for many witches and wizards, their whiskers can be grown to become very long. They say the whisker of a long-lived kneazle will create a perfect wand core for wands that are highly effective in casting Transfiguration and Conjuration spells.
Mandrakes are normally cultivated for their restorative properties, especially effective in curing those who have been Petrified. Now as a wand core, the Mandrake root is protective of sorts and is highly effective in casting defensive charms that rivals that of the phoenix tail feather. It’s been rumoured that holders of wands made with the mandrake root will have a certain resistance against Petrification as well, but it does not completely make them immune to the stone curse, however.
Phoenix Tail Feather
Another common wand core, Phoenix tail feathers are defined by their characteristic trademark of being highly versatile in defensive spells. Commonly used by Aurors and other wizards to defend themselves against the Dark Arts, the phoenix tail feather core provides a nice balance between counter-spells and charms. Using Curses and other Dark spells will often misfire or even backfire if used with a Phoenix tail feather wand.
Pixie wings are a great wand core for those who are by nature, impish. Perfect for casting Hexes and Jinxes, this is the perfect wand core for those troublemakers who’ve decided to take up a life of mischief. Pixie wing wands are also good with Charms and Transfiguration, for that extra “oomph” to make your professor pull her hair out in frustration.
A mischievous sort of core, Troll Horns have the frequency to be somewhat sporadic in terms of its power. On some occasions (especially when you only need a little push) you might find that this core will give you too much power, dealing powerful attacks and being unrelenting; while on other occasions you may find that this core will slack in spell strength. This wand is typically only used by those who have a great deal of patience as it takes time to bond. However, once bonded, this wand will never let its master fail.
Unicorn Tail Hair
One of the most common wand cores in the Wizarding World, unicorn tail hair is uniquely defined as a very passive and “healing” core of sorts. As expected, it has that extra boost in casting healing spells, and it isn’t too shabby in areas such as Charms and Transfiguration spells. However, it is not that compatible for casting Curses and other Dark Magic, and as such not many Dark Wizards use Unicorn Tail Hair for their wands.
Veela hair is becoming a bit more popular in Britain after its introduction to wand-making in the Scandinavian countries. Because of its exotic properties, Veela hair can give wands certain allure and charm that are greatly beneficiary to spells such as Charms, Hexes, and Jinxes. It has a tendency to be a bit stubborn at first, but over time and practice, you will find it rather easy to work out spells to your liking.