While in the Tree Gnome Stronghold, they have a Talk-to option, and will talk to players about the Khazard Battlefield and to join them in their cause.
Strangely, talking to them in the Tree Gnome Stronghold will make them say what they do on the Khazard Battlefield, where they will say "Can't you see we are trying to win a battle here?", even though there is no battle going on in or around the Tree Gnome Stronghold.