Mahapralaya was a cult leader of Entropy (a group that believed the world was headed to atropy and decay).To ensure his  members belived in it`s cause he and they infected themselves with many viruses and fatal diseases .Mr. Termineus met with Mahapralaya and informed him that the Nexus of Realities was shattered a embedded in Howard the Duck. Beliving that if they dismember him that would ensure Earth would fall into decay but they we opposed with Man-Thing and  Ellen Brant .He was eventually cured by a Nexus embedded Man-Thing that was vomited up by Howard .