The main bad guy in the Nestorian Infestation project, is the former Inquisitor Nestorian himself. Both him, and his most loyal followers have turned their backs on the Imperium and joined the Genestealer Cult. I want these guys to have the same look as the rest of the Genestealer Cult, but not as mutated. Instead of having a pice of bone-armour in their foreheads, I've given them small holes. These holes are actually bleeding wounds, where the four armed Emperor (the Genestealer Patriarch) touched them with his holy claw. The touch released venom into their bloodstream, slowly mutating them into hybrids. The hole in their foreheads also makes it easier of the Patriarch to make a psychic connection to his new followers.
Here are the first four models of the former inquisitorial warband: