They’re an Exemplar Chamber of the Anvils of Heldenhammer, so they field a lot of Paladins, among them Améline’s old Retinue of Retributors. It’s an old Chamber, and has fought through some of the fiercest conflicts the Stormcast have fought in the Age of Sigmar. They are named after the legendary folk hero, simply known as Blackhammer.
What’s agreed is that this figure was a hero, who constantly risked their life for the benefit of others, and yet somehow always survived despite the overwhelming odds that they were faced with, constantly cheating death.
A death god, and Nagash is the one that is popularly ascribed this role but it could have been another one, took this quite literally, and soon began hungering for Blackhammer’s soul, for a mortal to escape their clutches so many times had become a blow against their pride. However, no matter what this death god did, they could not prove that Blackhammer had prolonged their life with fel powers, or seize their soul by force. In the end, they opted for patience, for it seemed that Blackhammer still aged as all mortals do.
When Blackhammer finally breathed their last, the death god smiled, and waited in Shyish for their soul to arrive… But it never did.
The death god scoured the Realms, but could not find Blackhammer’s soul. It seemed that, however they managed it which no one to this day knows, Blackhammer had cheated death one last time.
The Blackhammers, being Anvils of Heldenhammer and thus constantly at war with Nagash, loved the version of this story where the Great Necromancer was the one that tried to take Blackhammer’s soul. They took up their name in their honour and strive to emulate them, both in heroics and in their defiance of death and its masters.

As of this moment, the Blackhammers are counted as destroyed, wiped out by Archaon’s forces at the All-Points during the events of BR: Morathi.

Herakes, Brother of the Stars, Anvil-Bearer, Who-Carries-The-Firmament-And-Laughs (like this title is a translation of a word from his old long-dead tongue), Herakes the Spirit-Forge, and many other titles, was the Lord-Relictor of the Anvils of Heldenhammer. He was an ancient folk-hero from the long-bygone days of the Age of Myth, a man attributed with many legends and tall tales, some of which are true, though when asked about them he’ll simply smile and move the conversation away from the topic. He guided the Blackhammers in matters spiritual, mental, and ethical. Valued for more than just his hammer-arm, he brought great wisdom with him to his Stormcast siblings, as well as a great capacity for listening. More than just a brother, he was a mentor, a friend to many.
He was the first one who figured out why Améline seemed to have lost so much of her humanity, identifying her deaths and Reforging on the Anvil as the cause. Herakes tried to limit her self-sacrificing tendencies to preserve her humanity, but he largely proved unsuccessful in this, much to his dismay. It greatly saddened him when Améline left the Blackhammers to become an Errant-Questor, but he had hopes that she would find success on her quest. He continued to guide the Blackhammers, and always had time to give that guidance to Améline whenever their paths crossed.
His life took a drastic turn in a battle against Ossiarch Bonereapers. He perished during that battle, itself not an unusual occurance, but this time his soul-lightning struck a Morghast mid-flight. Somehow he fused with the Morghast, and his whole soul overpowered the fragments of the others, gaining incomplete control.
In his confusion, all he remembered was that Améline was in Misthavn. Warring against the original personality of the Morghast unchained from Nagash’s domination, he took flight towards the City of Scoundrels to reunite with his Stormcast sister. Along the way the Morghast-Herakes would meet up and travel with a pyromaniacal grot called Snazag.