Undermarket

The Undermarket is "an otherworldly bazaar offering all manner of goods and services, all temptations a man could imagine and several he couldn’t. Anything can be purchased there if one is willing to meet the price, which is rarely monetary; blood, firstborns, and souls (yours or someone else’s) are all accepted forms of currency." It is accessible both in Countermay, where the Merchants of Esh have taken up shop, and Fartherall, where access to the Undermarket has caused wars.