Shadow AT-AT

Shadow AT-AT
A specially modefied AT-AT that is used to transport Shadow Stormtroopers and dark troopers to a battle field. It is painted black and caries anti-aircraft turrents, a point-defense laser system, a concussion launcher, an ARC caster, and a two Star Destroyer grade laser cannons. Also it carries a shield generater. Another ability it has is that it can divert all shield power to the laser cannons in a deadly burst capable of piercing shields.

Behind the scenes
One was possibly spotted at the battle of hoth if you look carefully in the backround during the AT-AT invasion.