From the original article here:

“We have done well,” he said. “But in metal-work we cannot rival our fathers, many of whose secrets are lost. We make good armour and keen swords, but we cannot again make mail or blade to match those that were made before the dragon came.”
   –Glóin, The Fellowship of the Ring
Dwarves speak of Moria with longing and with dread. Therein lie treasures undreamt and horrors both ancient and powerful. For generations, the Dwarves whispered tales of its wealth, but none dared pass through its doors… until Balin. Taking with him two other members from Thorin’s renowned companions, Balin traveled to Khazad-dûm, passed its doors, and began new works there. At first, their works fared well, and they reported to their kindred outside the Misty Mountains.
When the Dwarves of the northeast no longer receive word from Balin, they call upon some of Middle-earth’s greatest heroes to look for the Dwarf and his fledgling colony. As your heroes explore Khazad-dûm, the first deluxe expansion for The Lord of the Rings: The Card Game, they will discover both the realm’s abandoned riches and its hidden perils.
Riches worthy of song
Flush with 165 new cards (including 3 copies of each new player card), Khazad-dûm contains a wealth of new player cards, enemies, treachery cards, and locations. Its nine encounter sets create encounter decks for its three new scenarios and form the backbone of the upcoming Dwarrowdelf cycle of Adventure Packs. While most of the locations from these encounter sets work together to immerse you in the dark and dangerous passageways that traverse Moria, these new locations also expose new creative ground within the game. When your heroes explore a Plundered Armoury (Khazad-dûm, 34), you have the chance to play a Weapon or Armor attachment from your hand for free. These will be welcome additions to your fellowship as enemies press in upon you from all sides, and the ability to equip your hero with an expensive attachment like Citadel Plate (Core Set, 40) may prove the decisive edge between death and the successful completion of your quest.
Another treasure from Khazad-dûm appears as a player card. Narvi’s Belt (Khazad-dûm, 3) is a fantastic, unique two-cost attachment for the Leadership sphere that will soon prove indispensable in new deck builds, joining the ranks of Steward of Gondor (Core Set, 26) and Celebrían’s Stone (Core Set, 27) as the keystones of different strategies. While the Shadows of Mirkwood cycle introduces Songs that grant your heroes resource icons for each of the four spheres of influence, Narvi’s Belt provides a more efficient means of granting alternate resource icons in any deck with a Dwarfcharacter. Resource versatility results in flexible deck-building, and you may be able to better focus your heroes toward their strengths even as you draw upon the best supporting cards from all four spheres of influence to aid them on their quest.
Uncover the hidden perils of Khazad-dûm
The doors of Khazad-dûm will open soon. In the meantime, keep your eyes peeled for future previews in which we risk a little more light down the mines of Moria…