The First Void Insurrection was one of the most important events to ever take place in Creation. It was initiated by Cyratel, known as the First Void Avatar. Cyratel's unique Persona, Erebus, allowed him to completely control the powers of Void. Using this power, he brought Void into Creation and began to infect all Worlds.
It didn't take long for war to break out between Void Avatar and the forces of Heaven, Hell, and Eden combined with the goal to stop Void and Cyratel. This war lasted for just 5 months, during which the Angels, Demons, and Humans suffered heavy losses to Void. Even the Colossi sent to fight back against Void became infected and turned on their masters, adding to the massive death toll.
The Insurrection was eventually brought to an end by Lord Knight Falken, who, using his special soulcraft, Voidwalker, to traverse Void, confonted Cyratel and Erebus, and battled the two. Falken successfully defeated Cyratel and sealed Erebus away in Void, but due to the battle, he was left weakened an unable to sustain his soulcraft, leading to him falling to Void. Nonetheless, Falken successfully halted Void, and with the sealing of Erebus, Void was unable to sustain a physical form within Creation, thus ending the First Void Insurrection.
In the aftermath of the Insurrection, it was foretold that another Nephilim would eventually rise up with the powers of Void, known as the Second Void Avatar, and that he would bring about another Void Insurrection. It was due to this prophecy, and due to the fear towards the powers of the Nephilim that resulted from the war, that the Angels, Demons, and Humans together brought the entire Nephilim race to the sword, destroying all Nephilim to make sure such an event would never happen again. Nevertheless, a small number of Nephilim managed to survive the Nephilim Purge, and continued their lineage.