Rapecrons
Rapecrons were introduced during a very interesting session of writefagging. Essentially, the Necrons captured a human woman, and they decided to "rape" her with metal probes, conveniently located between their legs. After the deed was done, they assessed that she was fit to become a pariah and was sent off for processing.
Rapecron lords prioritize the capture of humans bearing the pariah gene, which is rumored to be the work of the Deceiver himself. Using these humans, they intend to increase the size of their army and use their abilities to help destroy the influence of the warp.