I am afraid the character has been thrown under the rug, along with many other Storm of Chaos bits. Which is a pity, couse he was awesome in his own way. Even the version of his death, seems to be inconvinient for the current fluff, as it would mean that Mannfred Von Carstein is currently in possesion of a huge, undead northman army.
with Archaon executing tzeentch's one for being slow.
Which I found sad, as Melekh the Changer had the best fluff of all 4 Archaon lieutenants. Aparrenly both of these characters recieved a rather underwhelming deaths. Melekh beign cut down by his own master, after single-handedly braving the center of the Chaos Wastes, and outfoxing a Greater Deamon of Tzeench. While Crom, after giving Ironhide a run for his money, single-handedly uniting the largest force of northmen ever, under his own banner and leadership, stopming down on Krak a Karaz defenders, and generally being a humble badass, is now currently one of the many, faceless, chaos zombies among Manfreds new horde.