Dueling, or PvP Dueling, is is a feature included in Update 12 that provides the ability to challenge another player to a duel. Players can duel their friends or test new builds before entering Cyrodiil or dungeons.
Dueling can be done in any non-PvP zone. Duels can be initiated from the social wheel by selecting "Invite to Duel" or by typing
/duel <player name> with a nearby player. Once the opponent accepts the duel, a flag will appear and a countdown will lead up to the start of the duel. The duel ends when either player reaches zero hitpoints and the losing player will get a free resurrection.