This is Gaur Plain, from Xenoblade Chronicles. It is a huge field located on Bionis’ Leg. Shulk and his friend, Reyn, traveled here to reach Bionis’ head following the Mechonis’ assault on Colony 6.
In Smash Bros., the stage has two long platforms on either side, with smaller ones underneath, all suspended above a giant, gaping pit. This stage undergoes a day/night cycle, and features the god Mechonis in the background.
Text by HyperShadic999