Kardia: The Magic of the Heart
The magic art of Kardia was founded by the same trio of girls who founded the Order of Kardia, a group dedicated to the protection of society. They discovered that by using their emotions as a catalyst for magic, they could create something powerful that didn't depend on a user's aptitude of mana, albeit at the cost of the magic being rather unpredictable, as is the nature of emotion.
Risks
As noted, Kardia requires the use of one's emotions to power. While this provides a potent substitute to the dependancy of mana, it comes at the cost of the user's emotional state both affecting and being effected by their spellcasting. If the user's emotional state isn't good at the time of casting, the magic can distort into something dangerous, causing a risk to both the wielder and those around them. Also worth noting is the toll that the magic takes upon one's emotional state, with practitioners describing surges of emotional instability after use of the magic. The Order of Kardia was able to create a remedy to this, however:
Elenchos
To combat the instability of Kardia, the Order's Founders connected their emotions to a crystal, encasing the gem into an amulet that would then become part of their uniforms. The Elenchos works to stabilise the emotions of the bonded individual, ensuring that the crystal takes the brunt of the recoil that comes with using Kardia. The Elenchos serves as both a focus for the Kardia user and a badge of honor, letting those around them know who they are and what they stand for.
Potency
Kardia is a very powerful form of magic, able to compete with Arcane magic so long as its wielders are emotionally capable of withstanding its power. When the magic is in use, its wielders can perform all sorts of miraculous feats, from blasts to harm the threats to rays of restoration to assist the injured. The colors of Kardia often reflect the emotions that its wielder is actively experiencing and using in its casting, such examples being yellow for happiness, blue for sadness and red for anger.