The Astra Militarum (Imperial Guard for us grognards) has long had a history of "overlooking" certain mutations from the human norm and recruit "abhumans" into their ranks. In the current, and recent, editions you can still take Ogryns (large, brutish humans adapted to live on high gravity worlds) and Ratlings (AKA halflings or hobbits). In previous editions, Beastmen were also allowed, but they have since been dropped as an option. For my full Astra Militarum detachment, I wanted to include a unit of Ogryns as they make great battering rams, and it gave me an opportunity to try some slightly different conversions.
For my Cult Ogryns, I started with the basic kit, but decided rather than simply going with some forehead ridges as you'd see on the normal Brood Brothers infantry, the Ogryns would develop full cranial protection remnant of tyranids or hybrid metamorphs. I also decided to go with one Ogryn wearing a gas mask as that is fairly right for the overall army's theme.
