Check translation because I'm not sure of the name, which is 土古 (lit. earth old).
The naming problem in question is with 古戦場, which is the name of the GBF's Guild Wars event. It officially goes by the name "Unite and Fight", but people will call it anything from GW to UnF to even just translating the Japanese name straight into Ancient Battlefield. The 土 before it is because each instance of this event favors a particular element, in this case Earth (土).
tl;dr You can call it Earth Unite and Fight, Earth Guild War, Earth Ancient Battlefield, etc.
Updated
Snowman?Good job on the Earth Ancient Battlefield ♥