Lack of awesome demon characters is appalling in 40k - dunno about you, but I always found demons more badass, and yes, EDGY, than boring churchboys with crosses and exorcisms. Plus in 40k, demons are like sort of, mash-up of what is left of hundreds of people churned in the warp, sorta meta-entities, which explains why the warrior demons are always humanoid, more or less. A transcendent form of life of humanity, ey?
So this his obviously a Herald Bloodletter, a bigger-meaner version of the regular Bloodletter troops. I think that the current GW designs for bloodletters are too lizard-like, even with some goddamn scales, they're basically like red lizards with horns and skullface, which is neither imposing nor making much sense designwise, so I went for a more clearly humanoid design, even slipping into canine-ish, since in earlier fluffs Khorne was described as being dog-headed.
And though I hadn't come up with a name and a full backstory for the char yet, this is gonna be the demon that's really hardened in battles with the pesky Grey Knights, both in reality and immaterium alike, kind of tactician amongst them - he's gotten quite powerful due to aquisition of warrior souls to add to his entity, and he's taking no shit from any Dreadknights, if the broken horn and neckwounds are to say anything.