A horrible torture device. Not for the squeamish.
There are a lot of bad people out there. That is why we must torture you: to keep you safe.
Many and varied are the ways of extracting a confession or ending a criminal’s life, and the one usually follows the other.
Magic is a blessing and curse, life and death, birth and undoing, a goal and a way.
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.