The birth of an enemy

When replying to a distress call, the Space Marines of the Iron Strikers chapter broke protocol and traversed a banned path within the warp. During the trip the chapters Librarian started to feel the powers of the warp attacking the chapters battle barge. Not long later the entire ship was morphed by the powers of the warp, and the crew and Marines were mutated, some possessed by daemons. When the barge finally exited the warp the chapter master Malekath concluded that to return to the Imperium was to condemn all those who had survived to death. The taste of the warps power had freed his mind and he saw that the emperor had enslaved all Marines and people of the Imperium. Now he drives his warriors on, conquering Imperial planets and enslaving or killing any who won't fight for him. Now called the Iron Gods, Malekaths target, there chapters home planet...