Taking the place of the most insane primarch (Wh 40k)

Imagine waking up in a f***ing TUBE after going to bed to just realizing you are in warhammer. His old will hold no meaning here, for there is only war and death to be found here.
[author note: I'm a rather new author just writing this for fun. so if you find grammar errors just message me and I'll try to fix it]