This Lord Garmadon figure is constructed in the style of the Hero Factory characters on a "t" frame body. He's the four armed Garmadon from after his trip to the underworld, and he carries the megaweapon he created from the four golden weapons. Due to limited availability of accessories on Lego Digital Designer, this Garmadon does not appear with the skeleton helmet adorned with a bone on front, but if the set were actually produced, he would have that helmet.
Here is a slightly different angle for greater detail.
In this rear view, you can see how his second set of arms is connected to the back.