"Meeble Burrows is a reserved battlefield event within Ghoyu's Reverie, Ruhotz Silvermines, and Everbloom Hollow, comparable to Assault in the Aht Urhgan areas, divided into separate missions known as "expeditions." Expeditions have a wide variety of goals, many of which do not directly involve defeating enemies. Expeditions are split across several courses and each course has five levels of expeditions culminating in a boss fight against one of several unique Notorious Monsters. Additionally, there is one bonus boss expedition from each field area after completing all courses of expeditions entered in that field area."
http://wiki.bluegartr.com/bg/Category:Meeble_Burrows
It's pretty fun. Pretty much do it twice a month for a few hours.