The Lore of the Ursadons

In the early era of the 31st millennium, eons before the before the Ab-humans known as Squats got targeted by the Tyranid Hive Fleet known as Behemoth, Leman Russ was plagued with dreams of the races demise. Russ met with many of the Squats and told them of his vision. Superstitious leaders drove him away, but some of the older and more wise leaders trusted in Russ' actions. He would not have sailed the vast sea of stars to come to their planet just to jest. And so a small portion of Squats followed him back to Fenris. Russ withheld this undertaking from the rest of the Imperium, he is not one for secrets, but he knows that this action would be unsanctioned.
The Ursadons are now millennia later the grand forgers of the Fang on Fenris. Their entire culture is within or under the Fang hidden away in Under cities.
The denizens of Fenris don't know about these areas and only those whom the Great Wolf (Logan Grimnar) deems worthy gets told of the grand forgers of Fenris.
These master artisans are the heart of the Space Wolves unique technology, Helfrost, Frost weaponry.
Every Ursadon is taught to forge as a right of passage.
Because of their work they like to study the grand beasts of Fenris this allows them to better understand how to make better weapons that can fell monstrous creatures or armor that can withstand them.
Above all else an Ursadon Iron Gothi will hone his forging of the mighty Frost Blades made two ways; either the secret art of shaping True Ice, or of the careful crafting of a Krakens (Large Tyranid Bio-creatures) teeth.
When it comes to forging, the mighty Kraken is coveted, for it's uses are infinite.
The craft of Krakens is an ever changing art as they evolve and adapt fast, this makes for so many possibilities in the forges and alchemy labs.
For forging, Krakens are 'the' grand material. But they are also the greatest foe. Working with many beasts as raw material, has also given the Ursadons deep knowledge in how to kill such creatures. And thus the Ursadons are skilled in the slaying of many monsters.
An older or Ursadon (sometimes even a cub) would seek to take on the most terrifying of foes, in hopes for glory and song in Sagas. But all the Ursadons know that the most venerable trophy, would come from that of a Kraken.
As such Ursadons are used by the Great Wolf to take on many of the most powerful attacks from the Tyranids as their skill in attacking and destroying them is parallel to that of the Deathwatch, maybe even superior.