The Burdinadin, by their nature, draw most of their resources from the deep underground. Mining operations are conducted by Din in iron suits (or human mercenaries, just as often,) who venture out of the Spiritlocks to hack through stone and soil to clear out ever-more space underground.
The inevitable conflicts with the Goblins are often mercenary affairs. They Burdinadin don't acknowledge any Goblin state, and don't acknowledge any Goblin rights. Ironically, the most common mercenaries employed against them are of the one race the Burdinadin loathe above all others: The Ohanedin, their brutal cousins from the woods.
The Burdinadin themselves rarely enter the conflicts. Though they are actively clearing out territory for their own expansionism, they are not eager to fight those whom this expansionism harms, and generally put a high emphasis on border defense to prevent encounters. When they become involved, however, they don't pull punches. They have developed arquebuses with simple baffling devices, to prevent the sonic reverberation from causing cave-ins, and have even developed crude methods to apply the same principles to cannons, so that they can bring artillery into the tunnels, and shower their foes with grape shot for daring to oppose them.
Near in the Burdinadins' future is a backlash for the wanton destruction of the underground ecology that they have funded and perpetrated. The question is, can they survive it, or will it roll up their colonies, or worse, the Iron Glades themselves?
A prominent example is that Dace, being a huge mining superpower, and one that can cover thousands of square miles, has flooded the iron and coal markets through sheer output, and as such is crippling the export business upon which dwarves previously dominated, and forcing them more and more to rely on the work of their artisans for trade.
Culturally, they're a race of isolationists, small holds that fear and despise outsiders, and are constantly seeking a way 'home,' though they don't know exactly where their 'home' is.
Dwarves are more involved in the Goblin and Burdinadin side of things — the Underground. Things are starting to change, because reasons are developing, as we fill out the setting more and more, for the Dwarves to be involved in the activities of their neighbors, and even to conflict with them.
This is a problem, because of course Dwarves hate selling their weapons, tools, art, and other cool shit to outsiders, because every time they do it they run the risk of someone reverse-engineering their techniques, and ruining their monopoly. So the Dwarves now have a very good reason to hate the Dacians.
The result of this is, essentially, a secondary frontier in the underground, moving parallel to the receding frontier above. While humans and other powers push on the Burdinadin's surface holdings, they expand underground, where humans can't follow.
On the Goblins' side, this is an absolute disaster. They can handle punitive raids and the occasional adventuring party, but concerted efforts to extinguish their race in a region? That's new.
It wouldn't be a huge problem, except that the Goblins have been underground for so long that they've become part of the ecosystem. A keystone animal, so to speak. Without them, the underground spirals out of control, and dark creatures that should not have need to awaken emerge from the depths, searching for food that had formerly been provided to them in the form of sacrifice and ritual.
With the ability to function in spirit-corrupted areas, and the unique (at least among surface races) ability to see in the dark, the Ohanedin are uniquely suited to fighting the Goblins in the deep places, without relying on crude methods of illumination. These shadow-wars may be, if not the source, than a reinforcement of the Goblin idea of "The Horned Ones," terrifying hunters with protrusions on their heads who slaughter and devour their kind, but take the remains away.