Titanomachy

"...If I could describe this clash of power in one word...I would certaintly use...titanic...or cataclysmal. Either way...remember this sight...because I doubt you'll get a second chance, even in a hundred years."

- Invel commenting over Titanomachy occuring during the battle with Bradman against God Serena Titanomachy (魔霊気巨人 (ティタノマクヒー), Titanomakuhii lit. Magical Aura Giant) is an exceedingly rare Magic Phenomenon that can only take place when two mages of ridiculous power clash in both body and spirit, resulting in titanic imagery that occurs at the height of a battle. It is essentially the world reacting to immense, environemntally warping powers of two mages, and giving them "form", heightening a battle's intensity and stakes.

Description
Titanomachy only takes place when two Mages of ridiculous power clash, and reach the height of their battle, where their body and mind begin to reach its peak intensity, resulting in an incredible exertion of magic power that begins warping the environment. This results in the two aura clashing, and due to the battle's intensity, the incredible magic power exerted, as well as the fighting spirit of the two mages, two titanic visages are created for the two combatants, taking a form most fitting and representative of them, which are colossal in size, and can vary in appearance, capable of interacting physically with the world.

From this point on, an enormous radius of the environment is scorched by intense magic power, with only the two combatants being unaffected, while every other lesser mage would be disintegrated or severely damaged by the unstable and intense power. The titanic visages created mimic the movements of the combatants to a perfect T, no matter the appearance they take, turning a simple battle between two mages into a world-shattering duel between giants. As expected, this would more often than not mean total destruction would spread, even moreso than before, spreading unfathomable chaos into the area, even affecting the environment, creating what can only be classified as natural disasters, depending on the magic employed by both mages, as elemental magic most commonly brings about these disasters. Only after the battle ends do these aura titans vanish, but can leave the mages incredibly burnt out on their magic power.

As stated prior, it is an incredibly rare occurence, as even two Saints battling cannot bring about this event willingly, thus presumably requires far greater power than that, as well as both combatants' fighting spirit to be at its height, and their auras as well, to trigger the chain reaction that brings about Titanomachy.

Trivia

 * The concept was partially inspired by the chapter that showcased Jellal's immense rage and power altering the skies from daylight to starry night skies.