Drugs

From publisher blurb:

From wealthy merchants and kings to lowly street urchins, people from all walks of life have become addicted to drugs both potent and mild. In some cities, entire gangs and even guilds are devoted to the creation and distribution of certain drugs, becoming ever more powerful as the masses become addicted. Other drugs are so rare or difficult to craft that those with sufficient wealth hire adventuring parties to seek out their ingredients. Some drugs give their users a mild euphoria, while other more powerful drugs have significant and even magical effects.