During the recent Norsca faction reveal Creative Assembly teased the upcoming arrival of an "old friend". As it turns out, the old friend is the former champion of the Blood God himself, Krell the Lord of Undeath. Not exactly my first pick as far as friends go, but I suppose he does come quite handy in a fight.
Krell is now available as an exclusive summon for the Vampire Count Legendary Lord Heinrich Kemmler. While he does constantly decay on the battlefield Krell is an incredibly powerful fighter that's fully capable of cleaving straight through entire legions of enemy infantry. He's also quite strong when it comes to facing down enemy heroes in 1v1 duels, though he will need a couple of buffs and heals from Kemmler in order to not crumble into dust mid-way.
If this sounds like the sort of thing you would love to play around with, but you don't actually own Total War: Warhammer, you're in luck as this update has also brought with it a Warhammer themed sale on Steam. You can find Total War: Warhammer at 66% off, and all of its DLC at 33% off. The DLC is not mandatory by any stretch, but I would recommend you give Total War: Warhammer a shot as it really is a great game. Have fun!