It's a good read by any mean, but there are a few issues I wonder about.
The Elysians shall be elite paratroopers, they seems here like they are cattle not elite soldiers. The followers of Chaos being organized, that sounded so odd that I at the first read assumed them to be Imperials. Okay might be my interpretation, but I would have added a section where Haum bested Kolan and such.
And there were a place were Haum was described as yelling something in praise to Khorne. Why not let him yell Blood for the Blood-God! or that other catchphrase they use? I mean Khornate fanatics are fanatics. They yell one phrase really loud.
Also the fighting, Haum seems to be heavily armoured. He should go in and feed the guardsmen their entrails not just shoot at them. He is a Khornate fanatic, and that would seem more like them. I can understand the need for him to take out alot in ranged combat, but if I were you I would have Haum topple a column or a statue of Empy on the hapless Elysians, and then you can add some humor in it was the Empror squashed his own weaklings.
Welp first of all, I dont intend to write my main character as a traditional chaos fanatic, second, he is of a military outfit who are comprised of professional troopers, Haum is a member of this and a veteran, which I will be revealing later.
I never said he was a khornate fanatic, I never implied it, I clearly explained there is a pantheon star as a medallion a sign of the follower of the pantheon undivided and he prayed to the pantheon before meeting the Elysian's charge. He happend to call out Khorne's name because he was in combat and since that is the war god's realm I thought I would add that in.
As for the Elysians, they charged into a house and Haum was in a position not directly in front of them to have been initially noticed, he took advantage of his angle and got a few lucky shots, I explain that. The third who charged him with the bayonet was already hit, thus the weak thrust of his bayonet, I also explained this I assumed with the howl when the three rounds hit his cover.
I dont want to potray him as a fanatic as I potrayed the newbloods (taking trophies and fingers) he is more disciplined and pragmatic, he isnt stupid, thus signifying his need to survive not only by luck but by thought and of course plot armour.
Also it just wouldn't be sensible to have a statue of Emperor still standing in a world occupied by Chaos forces, as well as the fact that Elysians arent the only soldiers in the place, I explain there are tanker companies and other infantry.