Magic Contract

The Magic Contract is a new type of magic developed by Shiroe as part of his Overskill, Contract Art Ceremony.

Overview
The Magic Contract is a document that allows Shiroe to create magical spells that did not previously exist in Elder Tale.

In Rundelhous Code's case, Shiroe used Phantasmal-level items such as paper from the Fairy King and ink from the Time Dragon's Eye. Due to his level 90 skills as a Scribe and his vast MP pool, he was able to re-write a fundamental law of Elder Tale, thereby creating a form of Global-Scale magic. As a result, he keeps this ability a complete secret due to ramifications of such an ability.

However, there are limitations on the scope of magical contracts: the power of a magic contract is in direct proportion to the rarity of the materials used to create it, and to the amount of MP consumed. Rundelhous' contract used up nearly all of Shiroe's MP in one move, and that was factoring in his natural higher MP from race and class bonuses, as well as his equipment effects. Furthermore, both parties must agree to the contract and sign it; if the other party did not fulfill one of the two requisites, the contract will not work.

Return of the Goblin King arc
Rundelhous Code was mortally wounded during the defense of Choushi Town. Though his body was saved by the healers of his party, his spirit had already left. To save him, Shiroe used Revival Incense to temporarily force his spirit back into his body, then have him sign a Magic Contract that Shiroe had created, using the top-quality materials he had gathered previously when Elder Tale was a game. As a result, Rundelhous was given the subclass of Adventurer and was revived at the Cathedral.

Gold of the Kunie arc
After failing to negotiate with Kinjo the first time, Shiroe writes up another magical contract for when he reached Kinjo at the end of the Abyssal Shaft raid. This contract allowed him to use the Kunie's infinite pool of gold to buy up all the unowned zones in Yamato, and then return both that land plus Akiba's important structures to the Kunie clan, rendering them unpurchaseable by any of the Round Table's enemies and releasing them from the duty of maintaining those structures.