Sync

Sync, short for "synchronize", refers to two or more individuals or parties attempting to be placed in the same instance in cases where parties or groups are supposed to be formed randomly. This is done by synchronizing each player's clicking of the "Enter Battle/Mission" button. There are several places in Guild Wars where syncing can occur: Synching in PvP is sometimes considered "unfair" or "cheating", as a team with a synchronised build that can talk using voice-chat has a big advantage over a team that consists of random players with individual builds that can only communicate by typing and drawing on the map. Synching in PvP was supposedly fixed in the September 1, 2009 Update.
 * In the Random Arena or in a Competitive Mission, players sync in order to be placed on the same team.
 * In an Alliance Battle, multiple groups of four players can sync in order to enter the same instance.
 * In the Vizunah Square and Unwaking Waters missions, parties in opposite outposts can sync in order to enter the same instance.

Synching in PvE however can be the only way not to be teamed up with a group of henchmen in two-party missions. Although in Normal mode there often is another party, in Hard Mode usually there isn't. That is why it can be very helpful to sync with some other player or team when going for guardian, as henchmen do not perform very well due to their lack of defensive skills.

Syncen