Spoiler: In the lore, Dork Redeye (the orc shaman/warboss) leads a WAAAGH into Mourkain and steamrollers over the Strigoi. Ushoran kills him, but dies in the process.
The same thing would have happened in Blood Dragon. Dork, who we last saw in W'soran's slave-pens, escapes Crookback Mountain and, with an army of proto-black orcs at his back, goes Spartacus on the Strigoi. The Lahmians (and W'soran/Melkhior) help divert the WAAAGH into a civil-war wracked Strigos, leading to its destruction.
In the book, we'd have learned that the only thing keeping Ushoran from giving in to the Crown of Sorcery completely is the fact that if he does, the Crown will exterminate all life in Mourkain, so as to have fodder for an undead horde the likes of which the world has never seen. Ushoran has been fighting to keep the Crown under control since he put it on, in order to protect Mourkain and his people, but it's a losing battle. And now he's stuck--he can't use the Crown against the orcs, because there's a very good chance that he'll be condemning his own people as well, and the longer he *doesn't* use it, the more likely it is that the empire of Strigos is doomed anyway.
Abhorash has stayed loyal to Ushoran because (a) he knows what the Crown's doing, because instead of scheming, he...well, asked Ushoran, and (b) he already let one empire go down in flames and he's not about to abandon a second. Essentially, through Abhorash's POV, it's revealed that while Ushoran is in fact a double-crossing, duplicitous sneak, he's also a *very* good king. And one who cares for his people, in ways that neither Neferata or W'soran noticed, being too intent on their own schemes (because who do you think taught the Strigoi about advanced irrigation techniques, public sanitation and law codes...W'soran? Ha! No.). Abhorash, having no schemes to speak of, did notice, and approves, albeit grudgingly. So he tries to help Ushoran control the Crown in order to save Mourkain and Strigos. This mostly involves stirring speeches.
Unfortunately, it all goes to pot, thanks to Neferata and co. The orcs attack Mourkain, and as Morath and Gashnag organize an evacuation, Abhorash tries to free Ushoran from the Crown. Which he does. But not without consequences. Ushoran is a shell of what he once was, and even worse, the Crown is *still* calling to him. So, he turns the Crown over to Abhorash, tells him to save as many of the Strigoi as he can, and goes to tear the heart out of the WAAAGH in person.
Ushoran gets a big damn hero moment, which ends with him (as in the lore) killing many wyverns and orc chieftains, and then the final battle with Dork Redeye, which ends with the obliteration of both, and the ruination of Mourkain. But the Strigoi survive, to scatter into the hills.
And that'd have been the first third of Blood Dragon.