Players who wish to duel must speak with Nek the Brawler at the inn in New Tristram, who will transport the party to the Scorched Chapel, a new area designed specifically for dueling. Scorched Chapel has four areas, the church, graveyard, river and lake, and supports up to four players in free-for-all battles. Dueling doesn't offer any rewards aside from bragging rights, and death in the dueling area isn't permanent, even for Hardcore players.
Other updates in patch 1.0.7 include class updates, crafting additions, monster power and affix changes, and quality of life improvements. Check out the entire preview list here.