"Far over the Misty Mountains cold, To dungeons deep and caverns old, We must away, ere break of day, To claim our long-forgotten gold."
- – The one poem from the Hobbit, which is the first, but not the last J. R. R. Tolkien reference on this page.
Belegar Ironhammer, The True King of Karak Eight-Peaks, is the current leader of Clan Angrund and is the last Heir to the throne of Karak Eight-Peaks. He also is not called Thorin and isn't friends with a hobbit, and if you try to say other wise you can expect a visit from GW's legal team and a spot in the "Dammaz Kron".
Belegar is a direct descendant of King Lunn who was the last king
under the mountain of Karak Eight-Peaks before it fell into the hands of the Goblins and Skaven. Born into a people with no home and who had to squat in Karaz a Karak, Belegar got bored of sleeping on people front doors and under rail tracks, and when he came of age vowed to retake his ancestral home. This wasn't an original idea as pretty much every other member of Clan Angrund with a claim to the throne had vowed to retake Eight-Peaks and settle the grudge, almost all of whom had died while trying. Luckily for Belegar, he had spent most of his time as king of the hobos fighting and leading Clan Angrund and this had made him a phenomenal fighter, to the point where he was compared to Ungrim. His quest was also backed by the High King Thorgrim Grudgebearer as he had persuaded the other Dwarf holds to send portions of their military to strengthen Clan Angrund in the task of retaking Karak Eight-Peaks, as Thorgrim saw the opportunity of retaking the lost Karak as a way to strengthen the Dwarfs power against their enemies and a way to cross out a fare few grudges at the same time.
So with an army at his back Belegar set out to reclaim his mountain (but without the Wizard and hobbit, because magic is for fags and Halflings are thieving little toerags who would nick all the gold). The combined strength of Belegar and Thorgrim’s armies made short work of the Orcs and Goblins on the surface and allowed clan Angrund to get their foot in in the door and retake parts of the upper levels of the Karak, including the Kings Hall. After this Thogrim returned to Ever-peak and told Belegar to continue the war effort, leaving clan Angrund to fortify and prepare to hold onto what they had captured.
Since then Belegar has been slowly retaking parts of his ancestral home and repelled multiple Goblin and Skaven attacks, during which he became extremely familiar with the cunning Goblin Warlord Skarsnik and the insane Skaven Warlord Queek Head-Taker, and has been forced to personally deal with the sneaky git on multiple occasions. And so Belegar fights, reconquering his home, inch by inch, battle by battle. And with an army at his back and wife at his side (oh yeah, he has a wife called Kemma, and later a son and it's one of the few loving relationships in dwarf society) he was slowly but surely taking back Karak Eight-Peaks. Though depending on who you ask, Belegar’s grasp of reality seems to be slipping as he grows more and more desperate to keep a hold on the territory he does have while still trying to push deep into Skarsnik and Queek’s territories.
The End Times had his quest end in failure, with him and his Hammerers ground down and surrounded by the sheer numbers of Clan Mors until Queek and his Red Guard find the moment to make the final strike against them. Queek had his troops form a ring of spear points around them to let him and Belegar duel. Exhausted and injured, Belegar was inevitably doomed against Queek, though he gets to enrage Queek by calling him far too inferior to hope to defeat him at full strength and still managed to stab Queek in the armpit with his own sword before Queek kills him.
Belegar is a little odd rules wise, not because he has any outlying rule that really sets him apart but because the exact opposite is true. Belegar is extremely generic when it comes to his rules, as he's in essence a pre-made maxed out dwarf lord for your army. He has all the same rules and stats to a generic dwarf lord, with the exception that he has Stubborn and his slightly increased weapon skill. He has Gromril armour and an Oathstone, along with a magical shield that gives him that tasty 2+ armour save, and said shield also gives him a 4++ ward save and an immunity to killing blow. The Hammer of Angrund has Always strike first and adds 1 to wound rolls meaning he's very capable of dishing out damage to his opponents and once per game, he can double his attacks from 4 to 8. So overall he seems pretty good, right? Well..... he's ok.
The main problem is that Belegar offers nothing unique in terms of play style or fluffy army building. Now let me tell you about good named characters, and how they should be made. The reason a named character should exist is because of three reasons, 1) they offer a unique way to play armies based on their fluff, for example Ungrim Ironfist lends himself fully to playing a Slayer based army as he gives buffs to Slayers and his rules and equipment makes him a buffed up Daemon and Dragon Slayer. If you bring Ungrim to the table, you need to invest the points into bringing some slayers as well so you can get the most out of him and maximise his armies effectiveness. This is both fluffy and crunchy in rules and army building. The second reason is if they have unique rules based on their lore, for example Valkia the Bloody. Valkia doesn't really buff your army outside of a leadership re-roll, nor does she force you to bring multiple Khornate units to get the most out of her, she is however a very unique character in the Warriors of Chaos army as stats wise she is half way between a Chaos Lord and a Daemon prince and has unique magical items and rules that can't be replicated with a generic lord. She can fly around the battlefield with her killing blow spear and is excellent at character and monster hunting. You don't have to build your list around her, but you do have to understand what she excels at and where she lacks. The last is being a character that functions similar to a generic but is more powerful and more expensive than any generic is capable of being like Settra or Archaon who are the big cheeses of their factions. Why is this important? Because Belegar lacks any of these fluffy or unique rules and has no defined play style which makes him a bit dull and easily out shined by other named characters. You would think with his fluff he would have rules that buffed Longbeards or Iron Breakers giving him a distinct play style, but he since he doesn't he's stuck with his very generic rules which means he struggles to justify his points vs a Dwarf Lord that you can tailor to your own tastes.
Now with all this said, Belegar is roughly the same price as a maxed out Dwarf lord built and he has a few extra bonuses in there, so you won't really lose anything by picking him over a generic lord, but you won't really gain anything either.