Neroth
Eliphas' nagging wife. He sucks, but if you can get the Artifact of Ahriman in the campaign in Retribution, he shits free doombolts everywhere and becomes half way useful. Of course, you'll probably have Eliphas at level 10 and fully Khornate at that point, so he'll be one-shotting entire armies with Sweeping Doom long before then.
He's NOT SINDRI. GET THAT THROUGH YOUR THICK SKULLS. SINDRI WAS AWESOME AND SMART AND SCHEMING, NEROTH IS SOME ONE-DIMENSIONAL IDIOT CUM-GUZZLER WHO'S THOUGHT PROCESS DOESN'T EXTEND BEYOND 'I WANNA BURN SHIT'.