The serum was a degenerative substance that temporarily inhibited the prions allowing experiments to use their powers. Because it disrupted the proteins within the body used to generate the powers, it only stopped psionic powers, not cybernetic ones. It also only stopped the powers temporarily.
It was made by the surviving members of the Anti-Dragonstorm Alliance at Crimson Base in September 2009. Siberys volunteered to be the experiment they tested on because he no longer wanted to have powers; he disliked how it caused all others to ostracize him. Ultimately they were successful in creating the serum, but due to the airstrike that murdered almost everyone in Crimson Base only a prototype clip of bullets were made. Wayne Anthony and Siberys brought these bullets in a pistol to James Zanasiu while he was staying in a hotel.
James brought the pistol to the oil rig and while there gave it to Sharon Varma, who used it to kill a Dhole experiment. Later she gave the pistol to Mitchell Crota who robbed Breathtaker, Stalker, and Deathwind of their powers at a crucial moment, causing their deaths. However he used up all the remaning bullets doing so. (Disruptive Selection)