The Proto-Corruption (officially designated Project SO-6, and derivatively nicknamed "Oilblot" by those that fought it) was a biological experiment by mad Dark Jedi Aherk Formidonis, and his masterpiece over the creation of life, created from ysalamiri, Yuuzhan Vong, and orbalisk DNA. Initially intended to bolster the abilities of Force users, its side effects proved too malignant to make it truly useful, and it was shelved until used in an insane, bloody attack on the Jedi Temple on Coruscant. After a long time in operation, bonding to several hosts, the beast was slain on Dantooine.
Project SO-6 was originated on Kamino, where the mad scientist Aherk Formidonis sought a way to augment his mediocre Force potency, with the hope of enabling him to best stronger opponents, while at the same time negating their own Force power. Starting by studying the properties of ysalamiri, which neutralized the Force surrounding it, and sending his personal droid KR-03 to capture a Yuuzhan Vong (a species also noted for their immunity and existence outside of the Force), Formidonis worked for months until he found a potent combination that utilized the best elements of both species. The comparatively simple organic compound, dubbed Phase One, negated all influence from the Force surrounding it when tested, acting much like a more potent form of miriskin.
Having developed a way to negate the powers of other Force-users, Formidonis' next step was to find a way to keep it from cancelling out his own. Traveling to Dxun, the Dark Jedi captured a number of orbalisks and brought them back to Kamino, dissecting and studying them; how they augmented the Force of the user, how they fed off of the midichlorians of the host, and how the relationship between parasite and host worked on a cellular level. Working nonstop for a far longer period of time and after much trial and error, Formidonis was eventually able to apply the organic Phase One compound to the orbalisks at a genetic level in a way that enabled them to maintain their usual nature while being immune to the very thing it fed on. These genetically-engineered orbalisks, collectively named Phase Two organisms, were eventually a success.
But it was in the final phase of Project SO-6's origin that Formidonis faced a problem that almost derailed the project entirely. Bonding with these orbalisks would be little better than bonding with ordinary creatures of the same species; eventually, they would multiply and suffocate him, missing the entire point of the biological weapon. Formidonis required a much more stable base in order to safely bond with and use Project SO-6. Searching high and low across the galaxy for almost an entire year, he found nothing that would solve his problem. Disheartened, but refusing to simply give up after all the time he spent in its development, Formidonis simply chose to create his own base.