The House of Crom is actually composed of two large dungeons. One is a social playfield that supports multiple simultaneous groups while the other is a six-man instance like those found in Khitai. The encounters take place in the bowels of the Eiglophian Mountains and are designed for endgame players. Lore-wise, the dungeon is an ancient Atlantean temple which has recently been unearthed (and defiled) by the Vanir raiders invading northern Cimmeria.
That's all fine and dandy, but what about phat lewtz? "We will be bringing in new Atlantean-themed items. Power-wise, the rewards will be on par with those found in the more difficult instances, and there will be all the regular token and trophy rewards that you would expect to find," says system designer Knut Jagels. The 3.0.2 patch is currently slated for the end of 2011, and you should head to the official website to check out the full dev diary while you wait.