Using a combined tactic of peer pressure and the promise of great things, he lured his enemies to high-class establishments and publicly ridiculed them - before making wagers that, if won, would completely reverse their fortunes and leave him in their shoes. He gambled his honour - but he always won, through a combination of underhanded tactics and simple misinformation.
Several hundred years later, Duchampe’s legacy of swindling and pressuring has been taken even further by the society set up in his name. The Duchampe Society prides themselves on being able to lower a man completely in the eyes of the world - and then quietly dispose of him. In this way, not only are their enemies - or clients - done away with, but their entire family’s name is dragged through the mud, effectively destroying every shred of honour connected with the departed gentleman in question.
The Society takes its business very seriously, and usually acts entirely of its own accord - although its services can be purchased in the proper circumstances. It does not deal with commoners or very high nobles, preferring to prevent modest businessmen from gaining too much favour with new ideas or boastful ways. Their favoured tactics are Duchampe’s own - placing impossible wagers with their own fortunes on the line, and then making sure that they cannot possibly lose. Generally they leave the actual killing to the losing party himself - suicide is all too common among the landed gentry of Dernwich.
There is no way to join the Society except to be born into it. The leading members dislike any form of inheritance besides nepotism, and take great care to groom their successors to the best of their abilities.