Negavolt Cultists are Heretek Cults that are often found on worlds controlled by the Dark Mechanicum. They fuse themselves with corrupt machinery that channels their own pain and hatred into arcs of Warp-infused energy that leaps from their electro goads. Negavolt Cultists also express their heretical devotion by despoiling machinery and corrupting the function of sacred technologies through daemonic invocations and abstruse rituals.
Due to their nature and relative importance in the maintenance and construction of heretical machines and Daemon Engines. Negavolt Cultists can be found in both Chaos Space Marine armies and the Lost and the Damned. Although in the case of the Chaos Space Marines, they are often overshadowed by either a Warpsmith or a Tech-Assassin.
In the Blackstone Fortress game. Negavolt Cultists are literally just a unit of four Electro Priests with a 6+ save in addition to the 5+ FNP. In an already melee focused Chaos meta, they are a hard pass. It might be a good idea to mount these fuckers on 25mm bases and call them Heretek Marauders, since their walking poses would make that easier than the regular Electro Priest's standing.