In the Demon Spawn War, Juiblex was killed several times by Covenant forces. These were always ugly battles, with many seeing their armor, weapons, and bodies dissolved by various puddings and oozes. Each time he was "killed", his Psychic Energy returned to the Abyss. It then went to one of his mindless "buddings" to start again. This required years to adjust to the new body, with rival demons always on the hunt for him in this weakened state. His last battle of the Demon Spawn War was with the Covenant general Melrith. In this fight, she used a powerful staff called Eldacil's Vine. She hoped it would end Juiblex's existence once and for all. It did not. Instead it led to lingering problems that still haunt Emeldimir and areas around the Lightless Cyst.
Juiblex became a cult power in the last centuries of the Horgon Era. Often fighting for the desire of the same dark-minded mortals, Melrith sent out her proselytizers to tell the truth of Juiblex. They were told they worshiped a ravenous slug, a beast with no sincere interest in his followers except to serve as food for his slimes, his black puddings and multitudes of other oozes. Most importantly, they were warned that he was a Demon Lord. One of those the ancient heroes of the Covenant and their mortal allies, battled to save the Quarat'un System from the demons. She was not alone. Tarâk also worked to remove Juiblex's cultists. His measures were more direct, eliminating those putting their faith in demon-kind. By the First Epoch, Juiblex had lost so much Divine Power that he was demoted, losing his position as a Higher Power.