Miasma

Miasma is a poisonous gas that once plagued the world of Auldrant in Tales of the Abyss. During the course of the story, the miasma resurfaces, prompting the world and the game's protagonists to contrive a solution to the threat.

History
The miasma first appeared during the Fonic War in B.D. 2699, when the use of powerful fonic weaponry placed a significant strain on the Planetary Storm, causing the planet's core to vibrate and emit the lethal, poisonous gas that eventually came to be known as the miasma. The war, in conjunction with the miasma, devastated the planet's populace, eradicating roughly half of the world's population. In B.D. 2709, the prophet Yulia Jue read the Planetary Score and predicted 2,000 years of history. She warned the warring countries the dangers of fonic weaponry and how the miasma would continue to spread as a result of their excessive use. Subsequently, the war ended that year.

A year later, with the land still greatly affected by the amount of miasma leaked during the war, Yulia, alongside her ten disciples, proposed the Float Project, a plan to raise the land utilizing the power of the Sephiroth Trees. When Yulia was arrested on a false pretense, the Float War began, a war waged by Ispania and Frank against those who endorsed Yulia's Float Project. When this war ended in B.D. 2713, Ispania and Frank emerged victorious, putting the Float Project into motion in N.D. 0001 (B.D. 2714), a new era. Upon raising the land, the countries' enemies were left in what became known as the Qliphoth, where the miasma still flourished. The new surface of the world eventually became known as the Outer Lands.