Some of the dwarven clans of Mystara have a sacred duty: building caverns, mazes, and labyrinths according to sacred and infernal geometries to trap the scouting minions of the Outer Intelligences -- the Hounds of Tindalos.
They are known as the Modrigswerg. According to the vaults of Pandius:
The Modrigswerg are an ancient clan of dwarves exiled from Rockhome for pursuit of forbidden lore and traffic with dark powers. Only the gnomes are their peers as artificers, but the Modrigswerg are said to be cursed by the Darkness, condemned forever to suffer distrust, treachery, and madness.
Modrigswerg reside in underground warrens in the hills and mountains of the Northern Reaches. They are aloof and generally dislike visitors. They share their race's traditional conservative attitudes, they are loath to abandon ritual, and adopt new ways reluctantly. They are masters of traps and fiendish devices; the best work in this field is done by Modrigswerg craftsdwarves.The tale of the exiling of the Modrigswerg clans always leaves out that it was a necessary and noble sacrifice, concocted by a council of clan heads, in order to keep creation safe from the Outer Intelligences. Their creations -- large and small -- are traps for the Hounds and other minion races sent to find and exploit entrances into our reality for their masters. Many of the works that adventurers encounter are, in truth, practice works, drafts, and experiments for their masterpieces -- designed to lure, trap, and kill these servitor races in elaborate underground cathedral-labyrinths.
These craftsdwarves skirt the madness of understanding the creatures and natures of the Outer Dark by hewing tightly to ritual, custom, and tradition. Any deviance from it is a sign of corruption, of succumbing to the taint of the Outer Dark, and is punishable by death.
There are rumors of a grand mega-dungeon in a dweomer-wrapped mountain where the Modrigswerg go to transform themselves into forever unchanging stone forms and stand forever as living batteries for their creations -- many of which are tied to their life forces to remain active.
These crafted items built to safeguard reality are built to last -- were it not for the chaotic, eroding, corrupting nature of the Outer Dark, they would have permanently safeguarded all of creation. But the Modrigswerg must wage an ever-escalating battle against their foes, and if the sentients of this reality must pay the price to unwittingly aid in this battle, then so be it.
In the LOTFP ruleset, the alignment of Modrigswerg dwarves are always Chaotic, due to their innate understanding of magics and how the magical planes and counter-planes arise from the interplay of surfaces between reality and the Outer Dark.