Azul’s unique magic, It’s a Deal (hidden meaning: The Golden Contract) is a “taboo” magic that “sucks every power out of someone if it’s not channeled through a contract.”
Azul does not need the scrolls in order to cast his unique magic: he needs them to limit it, as it is too strong for him to wield on his own.
In Book 3 Leona explains that Azul’s unique magic “enables the caster to take one power from a target if that target signs the scroll,” but he later learns that he was wrong and that the scrolls are merely the filter than enable Azul to control himself.
Leona further explains, “in the event of a contract breach, the breacher is compelled to obey Azul’s every command to a T,” and this seems accurate, with Azul turning 225 NRC students who fail to fulfill their contracts into servants in Book 3.
When Azul takes a special talent and/or magical power for collateral, “it’s sealed inside the contract and made available for Azul to use as it suits him.” Jack accuses Azul of cheating by using powers swiped from others, but Ruggie assures him that he isn’t: “As far as signature spells go, his is crazy high-level. Guy’s gotta have some chops to pull something like that off.”
We see examples of what might be abilities that Azul has acquired from other people via his contracts, such as an impressive singing voice, the ability to speak with and understand animals and advanced potion-brewing skills.
Leona says that the contracts last as long as the special scrolls he uses in order to limit his powers exist, and Azul himself emphasizes multiple times that they are invulnerable. When students attempt to so much as touch a contract they are electrocuted, with Azul saying, “they’re rigged to jolt anyone who touched them aside from myself.”
Leona says, “all magic’s got a loophole,” “there is no such thing as a spell that’s completely flawless” and that the idea that Azul’s contracts are unbreakable is preposterous, and he is proven correct: he is able to destroy Azul’s entire collection of contracts with his own unique magic, explaining, “it looked like they were impervious to damage only under specific conditions. Namely, either being in the VIP room, or being in your hands…the contract scrolls themselves are no stronger than any other sheet of paper.”
While Azul does not take the destruction of his contracts in Book 3 very well (it drives him to overblot), there are other examples in the game where he destroys contracts and does not seem to suffer any side effects.
Unique Magic Design: We technically see the process of Azul crafting his unique magic through sheer effort via a flashback: unlike Riddle, who seems to have worked for his UM to please his mother, and Leona and Idia, who were born with their magics, Azul seems to have been motivated by a desire to enact revenge on those who bullied him as a child.
But while Azul seems to have designed the spell himself, it’s possible that he didn’t know he was creating what would become his own unique magic at the time. While unconfirmed, he may have wanted a spell–any spell–to take talent from others, and it becoming his unique magic was possibly an unintentional bonus.
Limitations: During Glorious Masquerade Jamil teases Azul with, “I doubt a certain someone could get plants to sign a contract for his signature spell.” As Azul does not need the contracts in order to cast the spell, just to control it, it is possibly still unclear if he can or cannot cast his unique magic on things that cannot give their consent (maybe not without overblotting?).
In-Game Examples: Jade and Floyd describe examples of Azul’s unique magic from before they enrolled at NRC, with one mermaid losing weight in exchange for giving up their singing voice and another mermaid getting beautiful hair but losing their tailfin.
Other examples from the game include Azul contracting with the prefect in Book 3 to try and get them to acquire a photo from an elementary school trip on display at a museum in exchange for freeing his 225 student servants (including Ace, Deuce and Grim), taking Ramshackle Dorm as collateral.
He also contracts with Floyd, taking Floyd’s unique magic as collateral while granting him a deeper voice. Azul also contracts with Deuce, taking his unique magic and using it to strike Rollo in exchange.
There is a conversation in a vignette where he discusses providing Vil with moisturizer in exchange for poisonous plants from Vil, and while Vil does sign a contract there is no talk of collateral, so this may have been a normal exchange of favors between two Housewardens rather than a unique-magic-enforced arrangement?
Twisted Wonderland Reference Note 