Use of Magic is the ability to harness magic to cast spells, however, using dark magic corrupts the user. Powerful magical practitioners like Cora, Regina and Rumplestiltskin become corrupted by their powers and in turn, their magic turned tainted as well. Not all magical practitioners are corrupted, however, such as fairies, but they are exceptions because they cannot use magic in negative ways, instead of choosing to not do so. ("Once Upon a Time: The Price of Magic")
Magic can be used to override the usual laws of nature, physics, and reality, but it always comes with a price. It is inherently neutral and cannot itself be split into Good or Evil, but can be used for either purpose. Since magic use is powered by emotion, the strength of the spell depends on the feelings of the caster focuses into the output of magic. Negative emotions are generally used to power spells while positive emotions are used to maintain control of spells.("The Miller's Daughter")
However magic can be split into Light and Dark, forms of magic that are powered by positive or negative emotions, thus a manifestation of the wielder's will. However positive emotions do not equal goodness as a mage's attempt to protect one's loved one can result in a person's death- after all, the road to hell is paved with good intentions. ("Kansas")
Laws of Magic
The Laws of Magic define the limits of magical abilities. There are three restrictions even the most powerful magic is said to be unable to break: bring back the dead, force someone to fall in love and change the past. However, these laws can and have been broken and changed by powerful spells. One of them is the combined power of three genies who have overridden fate. This spell even makes the caster immune to the price of magic, but, it did not grant the caster the power to cause others to fall in love. Another case of laws-breaking magic is the time travelling spell that can be enacted by gathering symbols of wisdom, courage, love and innocence. ("And They Lived...", "Kansas")
Price of Magic
The Price of Magic is the inevitable expense for using or casting magic. Often stated as a warning that "magic always comes with a price", but sometimes, the price is not foreseeable. Rumplestiltskin's curse has the heaviest penalty for gaining his Dark One powers. While the magic allows him to accumulate masses of power, it corrupts him both physically and emotionally. ("Desperate Souls", "Skin Deep")
Other prices include the Evil Queen's sacrifice of her father to unleash the Dark Curse upon the Enchanted Forest. In doing so, she creates a void in her soul that can never be filled. At another time, Regina's attempt to outsmart and get rid of Emma by putting her under a Sleeping Curse backfires, as Mr. Gold predicted, when Henry is afflicted with the curse instead. Even Mr. Gold himself, who knows all too well there's always a price to pay, brought magic to Storybrooke, which returned his old powers, but the cost forces a barrier around town to form, preventing him from leaving to find his son. When Gerda asked for a powerful potion to erase the memories of her sisters, the price may have factored in causing her daughter Elsa to have her sister's powers. ("The Thing You Love Most", "A Land Without Magic", "We Are Both", "The Snow Queen")
Forms of Magic
Blood Magic is native to the Enchanted Forest. Its magic is linked to a person's bloodline and can be used in spells for hiding items from those who aren't of the caster's bloodline. The same method can be used to seal areas or locations. Rumplestiltskin uses blood magic on his old walking cane with a cloaking spell to hide a cupboard in his castle with some of his belongings in it, which Neal is able to open because he is his son. Regina seals her palace with blood magic to preserve it from the Dark Curse, but it is broken by the Wicked Witch of the West, who is her half-sister through their shared parent, Cora. ("The Heart of the Truest Believer", "Witch Hunt")
Fairy Magic is native to the Enchanted Forest and Wonderland and works differently from other types of magic in that it requires a reagent. This reagent, called fairy dust, is obtained by enchanted creatures called dwarves, whose purpose is digging diamonds from a local mine, which they collect and smash into powdered fairy dust. Then, the dust is gathered in large amounts by fairies to practice their magical arts. In some cases of advanced magic, fairy dust must be used through a wand. ("The Price of Gold", "Dreamy")
Good fairy dust, which is pink-purple in color, gives them the ability to accelerate natural processes such as a dwarf's birth, and to break an enchantment in which a person is cursed to stay in one form; such as in the case of Prince Phillip who was cursed by Maleficent into the form of a beast. Dark fairy dust is black-gray in color, is capable of transforming "deadly foes" into lesser and harmless beings. In Snow White's case, she uses it on a trio of trolls and turns them into cockroaches. Pixie dust, which is a more powerful type of fairy dust, gives the user the ability to fly and can also be used to find someone's soul mate. ("Snow Falls", "Dreamy", "Quite a Common Fairy")
Some abilities with fairy magic include the transformation of objects or beings, telekinesis and telepathy of inanimate objects. One notable practitioner of this kind of magic is the Blue Fairy. Her counterpart, Mother Superior, is also able to sense and detect witchcraft. Fairies have the ability to hide their wings from view as well as enlarge themselves to the size of a human, but according to the Blue Fairy, this must not be done without a good reason. ("The Price of Gold", "Dreamy", "The Stranger", "Quite a Common Fairy")
You awakened the Genie of Agrabah. You’re entitled to three wishes – no more, no less. But you must know, that magic has its limits. You cannot wish for life nor death, you cannot wish for love, you cannot wish for more wishes. And once spoken, a wish cannot be undone – no matter what the consequences. So, tell me your first wish.
Genie Magic is native to Agrabah where servants of magic, genies, have the ability to grant three wishes to any human that picks up their residing lamp or bottle. There are, however, some wish restrictions. One cannot wish for another person's demise by death, bring back the dead, make someone fall in love, change the past or use one wish to ask for many more wishes. ("Trust Me")
One such genie is the Genie of Agrabah, whose lamp is washed away to the kingdom of King Leopold. The king accidentally rubs the lamp and brings out the Genie. Despite being offered three wishes, King Leopold uses one of the wishes to free the Genie from servitude. Even after this, the Genie is able to use magic to influence an Agrabahn Viper to turn away from himself and attack King Leopold. The Genie becomes a Magic Mirror after being granted his own wish to stay forever with a woman he loves, the Queen, and gains the ability to spy on people through mirrors for her. ("Fruit of the Poisonous Tree")
Another known genie is Cyrus. He, too, like the Genie of Agrabah, always longed for freedom. Unlike King Leopold, Alice, who opens Cyrus' bottle, is heeded against using a wish to free him. In his own words, Cyrus states freeing a genie doesn't have a good outcome for either parties involved. After Alice and Cyrus fall deeply in love, she decides against using up the three wishes. ("Trust Me")
Ice Magic, also known as Snow Magic or Cryokinesis, is native to Arendelle. It is the magical ability of controlling and creating ice and cold temperatures for various purposes, that can go from creating living snowmen or giant ice palaces to freezing hearts and casting snowflakes. Only members of the royal Arendelle bloodline have shown the ability to use Ice Magic. Other uses of Ice Magic are molding them into various objects, from basic spikes and snowballs to more complex forms, such as mirrors and chains. According to Rumplestilskin, it's a very rare gift. In both generations, it was possessed by the eldest female of a set of siblings and who would become Queen, as seen with Elsa and Ingrid respectively. This magic can be specifically contained by the urn, which traps the user inside and seals away their power.
Ice Magic is loosely based on the magical ability featured on the Disney movie, Frozen.
Potionscraft is native to the Enchanted Forest as well as countless other worlds. It is the magical ability of creating substances for various purpouses. Such potions can be replicated when the user possesses skill, and the recipe, or a sample of the potion.
Seer's Magic is native to the Enchanted Forest. A mystical seer, in the form of a young child, is able to see future, but she only predicts the outcome or incomplete portions of her visions. She considers the power an unwanted curse, and later rids herself of it by passing the power to Rumplestiltskin. ("Manhattan")
True Love is the only magic powerful enough to break any curse.
True Love is native to the Enchanted Forest as well as countless other worlds. It is the most powerful and simple form of magic with capabilities of breaking curses through the act of true love's kiss as demonstrated when Belle attempted to lift Rumplestiltskin's Dark One powers and restore him to being a regular human. True love's kiss is also able to reverse effects of any negative witchcraft, such as Snow White's ingestion of a memory potion, which turned her into a cold and heartless person, but she was brought out of it when kissed by Prince Charming. ("Skin Deep", "Heart of Darkness")
In his endeavor to capture the elusive and rare physical form of true love, Rumplestiltskin sought out to make deals with both Snow White and Prince Charming. On both occasions, he took a strand of each person's hair as payment. Combining both hairs in a bottle, he successfully created a true love potion. At a later time, Rumplestiltskin seeks out Prince Charming again to hide the potion in a dragon's belly for protection. Twenty-eight years later, after the breaking of the Dark Curse, after Emma defeats a dragon and retrieves the potion, Mr. Gold steals it for his own use. He throws the potion into a wishing well and unleashes magic upon town. ("Heart of Darkness", "A Land Without Magic")
True Love is shown to manifest in various ways, which aren't neccesarily romantic love but more of family and friendship bonds. Simple looking objects can be infused with True Love and cause them to have some magical abilities, such as a two strands of hair from Snow White and Prince Charming allowed the Dark One to capture the magic in a physical form. Another example could be the ribbon which Ingrid and her sisters used to represent their unity in keeping their eldest sister's powers controlled.
As some practitioners of witchcraft can rip out another person's heart, those born as a product of true love have the power to resist such magic. ("Queen of Hearts")
Witchcraft is native to the Enchanted Forest as well as countless other worlds. It is a form of magic that requires the user to be adept in using spell books and incantations. When used, witchcraft often gives away a pink or violet glow and at times will manifest as a puff of smoke, which can be pink, purple, white, or black, depending on the user. ("Pilot", "We Are Both")
Witchcraft includes magical abilities such as telekinesis, which enables lifting and throwing people and objects, teleportation of oneself or others, making objects appear out of thin air and turning things invisible. Significantly, they can create and cast curses, such as Dark Curse and the Sleeping Curse. Witchcraft practitioners can also perform acts of transformation over themselves or someone else and create protective shields. ("The Thing You Love Most")
They can also perform acts negative to another being such as causing physical pain, immobilization or combustion. Further abilities include changing the basic nature of something, such as spinning straw into gold, or willfully conjuring an item out of thin air. Witchcraft practitioners are learned in making potions with various effects and enchanting objects to have special functions. Their magic allows them to cause physiologically impossible situations, such as cutting off someone's head without the occurrence of death or using healing powers to instantly restore someone to full health. In addition, they can also summon creatures such as a Wraith and erase memories at will. ("Skin Deep", "Hat Trick", "Broken", "We Are Both", "In the Name of the Brother")