This image was the first piece of concept art revealed after the first leak in November 2012.

It shows the enemy known as the Fallen. A spider tank trudges through the snow in the distance, and one of the figures appears to be shadowed by what might be a companion drone of some sort.

"Fallen" could also be seen as a reference to Bungie's RTS series, Myth. Myth's first title was Myth: The Fallen Lords.

It cannot be clearly seen in this image, but apparently one enemy variant, seen here riding the back of the spider tank, is called the spider pirate, and has four arms.