Far, far to the south, where east and west meet and become north, there is a valley, carven not by the slow slide of the world's rocky skin over her firey heart, but rather the wind and water have carven it, deep and narrow, folding away from the sun. Here, at its deepest depths, the Light never reaches. Here, at the top of the bottom of the world, lies the place which Shadow and Darkness have dedicated to themselves.
In a city where the justice system features judicial dueling, plaintiffs and defendants are permitted to request a champion to take their place in the duel: Someone chosen by lot from among the foreigners in the city. When anyone first arrives, they are given an enchanted ceramic pendant that marks them as a candidate for "court duty".
Wealthy folk entering the city are often escorted by burly guards, paid to carry pendants on their behalf: They elude court duty in that way.
Adventurers may seek work as a rich man's proxy or may find themselves magically summoned to serve as a champion.