So this is Oleghim, a deamon prince that Nurgle has tasked with the mentoring of Kaegr, the Sorcerer and Leader of the Harbingers of the Allfather.
He was originally a space marine of Abbadons warband. He was a champion of great prowess. And above all he acknowledged the power and worthiness of Nurgle. Nurgle blessed Oleghim, gifting him with unnatural toughness and endurance. Above even the mighty plague marines of Nurgle. Oleghim delivered plague, malady, bolt, and blade to the enemies of Nurgle.
During a raid on an imperial outpost Oleghim was singled out and beset by no less than 5 Ogrin. These brutes were easily a match even for Oleghim. And in the moment when a particularly ugly ogrin was about to deliver the fatal blow, Nurgle showed how much He truly favored the champion of chaos. In a great explosion of grime, and filth,Oleghim exploded 14 meters straight away from the ground, and the pack of roaring behemoths. Oleghim glowed with an unholy pale green light as his spine and shoulders distended and grew. His arms exploded into limbs the size of tree trunks, and his blade, now soot black, exuded an aura of pure terror as runes of plague and blight etched themselves upon the ebony blade. His armor and skin fused into one horribly tough layer of deamonic flesh. He doubled his hight and his helm grew and augmented into a leering, bestial face. His jowls grew wickedly sharp fangs, and his eyes took on a morbid pallor.
Stupid as they may be, even the Ogrin feared the spectacle unfurling before them. Before they could run, Oleghim, a daemon prince, declared "hail your destruction!"" The vanguard of Nurgle has been born." With that he whipped his sword in an arc and tore asunder two of the ogrin before they could twitch. In a blur of gore he dispatched the other ogrin, the monsters didnt even make it four steps. And for the next 2300 years Oleghim has proved himself worthy of Nurgles trust time and again. And now he guides one of the Plague Fathers newest projects. The Harbingers are destined for great things. And it is Oleghim who will help insure Nurgles purposes are manifested.
http://www.dakkadakka.com/dakkaforum/posts/list/0/380694.page#3037674
The above link goes to my Typhus painting log. It also containes the fluff for my Harbingers of Nurgle. A space wolves company who learns the dentity of the TRUE all father, and swear allegiance to Nurgle