Vulkan, the Primarch of the Salamanders.
Drew this as a prize for a contest held on a great place to talk 40K online: Bolter & Chainsword. The winner: a nice fellow that goes by the name of Brother Dakath.
You know this guy's backstory, so I'll focus on the drawing.
First things first, no way was I going to fit Vulkan inside a lowly Power Armour, even one custom-made for a Primarch. He's supposed to be one of the strongest among his brothers. So I got him a Terminator armour, albeit without the usual "cabin" above his head.
I tried to make him pretty menacing and primal. Vulkan's often portrayed as being on the tamer side of the Primarch spectrum, but he was raised in a world of fire and constant natural catastrophes, fought off Dark Eldar and giant lizards, while living with a good but certainly hardened people. So he might be a nice guy, but he won't exactly think twice before dealing with any enemy in old Imperial fashion.
The flamethrower-gauntlet got changed, since the one Vulkan He'stan carriers is...pretty meh. So I turned it into a saurian mandible.
The other weapon, the hammer...well, Vulkan is a man marked by his fathers. So the idea was for him to have crafted an hammer in dark iron resembling his Nocturnean father's (a blacksmith) tool and to sculpt a father in each side. You can see his "first" father on the side of the hammer, toiling in his forge. I opted to show him instead of the Emperor to reinforce Vulkan's (and, later, his Legion/Chapter) connection to his people.
In all honesty, I think he's one of my best pieces. State your mind, guys.