Scrimmage

A scrimmage in the context of Guild Wars refers to a PvP battle held between members of the same guild or alliance. To initiate a scrimmage, a group of one or more players in the guild hall must click on Guild Battle and select "Host a Scrimmage Match". Subsequently any other group of one or more members may join the scrimmage match by clicking on the Guild Battle button.

There can be at most 8 players on one side in a scrimmage.

You can also gain experience by killing the NPC's of an opposing group.