Alright Mon-keigh, listen up. I'm going to let you in on a little secret that GW doesn't want you to know. Malal exists (but not really) and is the chaos god of non-canon and ret-con. You see, when the Emperor killed horus, it is said that the glorious mind-pimp-slap was so hard that the Warmaster ceased to become canon. Non-existant if you will. GW has not realized it yet, but what is known as "The first ret-con" inconsequentially caused the creation of a new chaos god: Malal Malal lives in a universe that is even crazier than the warp. A mirror realm where there is nothing but races that have been "killed off" by GW and planets have mysteriously disappeared or destroyed. What exists in 40k does not exist in the mirror realm and vice versa. History and battles like how the necrons beat the ultramarines or that terrible 40k fanfic you've read on deiviantart are also real in Malal's realm as they are not in this universe. The only way to pass between our universe and Malal's is to have GW ret-con you, or to bring you back from being ret-coned. Malal is easily the most powerful of ANY chaos god. Commanding entire races like the squats and is even in charge of three primarchs: Horus, and the two missing primarchs. Whatever is ret-conned becomes under his control. Take this secret and guard it well. Don't tell anyone or you very well might join his forces.