With hundreds of human colonies now razed in the wake of the Covenant War, the UNSC has dispatched large numbers of advanced pioneer groups to survey potential new worlds. The discovery of Eudemon X49-05 was considered lucky, but concerns remain about the moon’s structural integrity.

Erosion, also known as War Games Map_Set/: 773-9,[1] is a Forge environment available in Halo 4. This map takes place inside a cavern which has two man-made structures and terrain which naturally slopes down.[2]


This map houses two structures by default, of which one is a Grifball court and the other is a pumping station constructed on an overhang. The map features natural ramps and small caves, and offers multi-leveled terrain.

Beyond the second man-made structure, there is small lake over which players can Forge. Furthermore, players can also forge underneath the previously mentioned overhang. There are three maps forged on Erosion that are featured in Halo 4 multiplayer. These three maps are as follows: Temple, Sarges Lab, and Pumping Station. There are also two forge-made maps made on Erosion that are shipped with the game: Ascent and Grifball Court.