Magic Formula (術式 Jutsushiki, localized as Ars Magus and Armagus) is the use of science to manipulate Magic Element. The knowledge for how to perform each formulas is recorded in a Grimoire.
During the Great Dark War, Konoe A. Mercury of the Six Heroes passed her sorcery to mankind but humans were unable to use it in its basest form as they were not capable of handling or manipulating it. Therefore, in order to make use of it, humanity did a great deal of research into the subject and eventually developed what is now known as "Magic Formula". By using science to manipulate Magic Element that came from the Black Beast, Magic Formula could be used to many ends. In order to use Magic Formula, one would have to recite the formula, or "spell". When Magic Formula was first developed, the creators found that the power and effectiveness of a grimoire varied with its user. Since that discovery, mankind was able to produce more efficient Magic Formula. Unfortunately, Magic Formula alone was not enough to defeat the Black Beast and mankind knew they would need more power and developed Magic Formula Weapons and Magic Formula Armaments.
It was completed approximately within half a year, thanks to Yūki Terumi's massive knowledge of Magic Element and the Black Beast. As normal people do not posses the ability to manipulate Magic Element, a Grimoire, a type of converter, changes the gathered Magic Element within the Magic Formula.
Magic Formula suitability test
The Magic Formula suitability test (術式適正 Jutsushiki tekisei, localized as Ars Magus aptitude) is a simple test that is based on Magic Formula synchronicity. The test itself consist of activating a base Magic Formula. The aptitude is measured by the amount of Magic Element that the tester requires to activate it. An average person requires 20 units of Magic Element for the activation, while someone like Taokaka needs only 10.